Review of import conditions for fresh taro corms · In June 2005, Taro Growers Australia wrote to...

Review of import conditions for fresh taro corms

November 2011

© Commonwealth of Australia 2011 This work is copyright. You may download, display, print and reproduce this material in unaltered form only (retaining this notice) for your personal, non-commercial use or use within your organisation. Apart from any use as permitted under the Copyright Act 1968, all other rights are reserved. Inquiries concerning reproduction and rights should be addressed to Communications Manager, Biosecurity Services Group, or e-mailed to [email protected]. Cite this report as: Biosecurity Australia (2011) Review of import conditions for fresh taro corms. Biosecurity Australia, Canberra. http://daff.gov.au/ba Disclaimer: The Australian Government acting through Biosecurity Australia has exercised due care and skill in preparing and compiling the information in this publication. Notwithstanding, Biosecurity Australia, its employees and advisers disclaim all liability to the maximum extent permitted by law, including liability for negligence, for any loss, damage, injury, expense or cost incurred by any person as a result of accessing, using or relying upon any of the information in this publication. Cover image: Taro (Colocasia esculenta) corms imported from Fiji. Photographed by Biosecurity

Australia officer, Sydney, October 2010.

Review of import conditions for fresh taro corms Contents

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Contents

Acronyms and abbreviations…………………………………………………………... v

Abbreviations of units…………………………………………………………………… v

Summary…………………………………………………………………………………… vii

1 Introduction……………………………………………………………………… 1

1.1 Australia’s biosecurity policy framework………………………………………………….. 1

1.2 This import risk analysis……………………………………………………………………. 1

2 Method for pest risk analysis………………………………………………… 5

2.1 Stage 1: Initiation…………………………………………………………………………… 5

2.2 Stage 2: Pest risk assessment……………………………………………………………. 6

2.3 Stage 3: Pest risk management………………………………………………………….. 12

3 Commercial taro production and trade……………………………………. 15

3.1 Assumptions used to estimate unrestricted risk………………………………………… 15

3.2 Taro cultivation practices………………………………………………………………….. 15

3.3 The global taro industry……………………………………………………………………. 16

4 Pest risk assessments for quarantine pests……………………………… 19

4.1 Quarantine pests for pest risk assessment……………………………………………… 19

4.2 Fiji ginger weevil……………………………………………………………………………. 21

4.3 Taro beetles………………………………………………………………………………… 25

4.4 Taro planthopper…………………………………………………………………………… 29

4.5 Paraputo mealybugs……………………………………………………………………….. 33

4.6 Yam scale…………………………………………………………………………………… 36

4.7 Taro root aphid……………………………………………………………………………… 41

4.8 Spiral nematodes…………………………………………………………………………… 44

4.9 Taro root nematode………………………………………………………………………… 48

4.10 Needle nematode…………………………………………………………………………... 52

4.11 Bacterial blight of taro……………………………………………………………………… 56

4.12 Corm rot……………………………………………………………………………………... 60

4.13 Corallomycetella root rot…………………………………………………………………… 61

4.14 Black root rot………………………………………………………………………………… 65

4.15 Taro leaf blight…………………………………………………………………………….... 68

4.16 Taro pocket rot……………………………………………………………………………… 73

Review of import conditions for fresh taro corms Contents

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4.17 Pythium corm rot…………………………………………………………………………… 77

4.18 Colocasia bobone disease………………………………………………………………… 81

4.19 Dasheen mosaic……………………………………………………………………………. 85

4.20 Taro reovirus………………………………………………………………………………... 90

4.21 Taro vein chlorosis…………………………………………………………………………. 94

4.22 Tomato zonate spot……………………………………………………………………….. 98

4.23 Pest risk assessment conclusion…………………………………………………………102

5 Pest risk management……………………………………………………….. 107

5.1 Pest risk management measures and phytosanitary procedures……………………. 107

5.2 Review of policy…………………………………………………………………………… 111

6 Conclusion…………………………………………………………………….. 113

Appendix A: Initiation and pest categorisation for pests of taro………….. 117

Appendix B: Additional data for quarantine pests…………………………… 159

Appendix C: Biosecurity framework…………………………………………….. 169

Appendix D: History and classification of taro………………………………… 175

Glossary………………………………………………………………………….………. 185

References………………………………………………………………………………. 189

Review of import conditions for fresh taro corms Tables and figures

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Tables

Table 2.1: Nomenclature for qualitative likelihoods ............................................................ 8

Table 2.2: Matrix of rules for combining qualitative likelihoods ........................................... 9

Table 2.3: Decision rules for determining the consequence impact score .........................11

Table 2.4: Decision rules for determining the overall consequence rating for each pest ....11

Table 2.5: Risk estimation matrix ......................................................................................12

Table 3.1: Estimated production of taro in 2009 from the 20 highest producers ................17

Table 3.2: Top taro exporting countries in 2008 ................................................................17

Table 4.1: Quarantine pests for fresh taro corms from all countries ..................................19

Table 4.2: Summary of risk assessments for quarantine pests for fresh taro corms ........ 103

Table 5.1: Phytosanitary measures proposed for quarantine pests of fresh taro corms ... 107

Figures

Figure 1 Map of Australia ................................................................................................ iv

Figure 2 A guide to Australia’s climate zones .................................................................. iv

Figure D.1: A typical dasheen type large corm taro .......................................................... 179

Figure D.2: A typical eddoe type small corm taro .............................................................. 180

Review of import conditions for fresh taro corms Maps of Australia

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Figure 1 Map of Australia

Figure 2 A guide to Australia’s climate zones

Tropic of CapricornTropic of Capricorn

Review of import conditions for fresh taro corms Acronyms and abbreviations

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Acronyms and abbreviations

Abbreviations of units

Term or abbreviation Definition

°C degree Celsius

cm centimetre

g gram

ha hectare

mm millimetre


ACT Australian Capital Territory

ALOP Appropriate level of protection

APPD Australian Plant Pest Database (Plant Health Australia)

AQIS Australian Quarantine and Inspection Service

CABI Centre for Agricultural Bioscience International, Wallingford, United Kingdom

EPPO European and Mediterranean Plant Protection Organization

FAO Food and Agriculture Organization of the United Nations

ICON AQIS Import Conditions database

IPC International Phytosanitary Certificate

IPPC International Plant Protection Convention

IRA Import Risk Analysis

ISPM International Standard for Phytosanitary Measures

NSW New South Wales

NT Northern Territory

PRA Pest risk analysis

Qld Queensland

SA South Australia

SPS Agreement WTO Agreement on the Application of Sanitary and Phytosanitary Measures

Tas. Tasmania

USA United States of America

Vic. Victoria

WA Western Australia

WTO World Trade Organization

Review of import conditions for fresh taro corms Summary

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Summary

Biosecurity Australia has assessed the quarantine risks associated with the importation of fresh taro (Colocasia esculenta) corms from all countries, excluding those countries where the recently reported fungal pathogen Marasmiellus colocasiae occurs. This report proposes that fresh corms be permitted import into Australia, subject to specific pest risk management measures.

Following stakeholder consultation, some amendments have been made to the final report.

• Twelve new pests have been added to the categorisation table.

• An additional pest risk assessment has been included for the yam scale, Aspidiella hartii. • For spiral nematodes, the rating for probability of distribution has been raised from ‘Low’

to ‘Moderate’, and probability of spread raised from ‘Moderate’ to ‘High’. The resulting unrestricted risk estimate is ‘Very low’, which is still below ALOP and does not require application of additional measures.

• The rating for potential establishment of the French Polynesian strain of Dasheen mosaic virus has been raised from ‘Moderate’ to ‘High’, bringing the unrestricted risk estimate to ‘Low’, which is above ALOP, thereby requiring management measures to mitigate the quarantine risk.

The fungal pathogen Marasmiellus colocasiae, responsible for corm rot, has been identified through the categorisation process, but not enough information is currently available to adequately assess the quarantine risks. Consequently, imports of taro from Brazil and any other country where this pathogen is known to occur will not be permitted. The assessment of risk and the need for phytosanitary measures will be reviewed if an intent to trade is demonstrated and additional information becomes available.

Six quarantine pests have been identified as requiring additional quarantine measures to manage risks to a very low level in order to achieve Australia’s appropriate level of protection. The pests are taro planthopper (Tarophagus proserpina), taro leaf blight (Phytophthora colocasiae), colocasia bobone disease virus, the French Polynesian strain of Dasheen mosaic virus, Taro vein chlorosis virus and tomato zonate spot virus.

The proposed quarantine measures include:

• inspection of taro corms on arrival to ensure that quarantine pests and other regulated articles are detected and consignments are subjected to appropriate remedial action

• removing all petiole material and the apical growing points from corms of large corm taro (Colocasia esculenta var. esculenta)

• only importing taro corms sourced from areas declared free of taro leaf blight

• prohibiting imports of small corm taro (Colocasia esculenta var. antiquorum) from countries where taro leaf blight, colocasia bobone disease virus, the French Polynesian strain of Dasheen mosaic virus, Taro vein chlorosis virus or tomato zonate spot virus are present.

Review of import conditions for fresh taro corms Summary

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Alternative measures to the requirement to demonstrate area freedom from taro leaf blight will be considered on a case-by-case basis. If it is determined that the quarantine risks can be effectively mitigated by other measures, then alternative import conditions will be proposed.

The importation of small corm taro will not be permitted from any country unless they can satisfactorily demonstrate freedom from taro leaf blight, colocasia bobone disease virus, the French Polynesian strain of Dasheen mosaic virus, Taro vein chlorosis virus and tomato zonate spot virus. At this stage we are not aware of any country free of these pests. However, any application for access for small corm taro will be assessed on a case-by-case basis. If it is determined that the identified quarantine pathogens are absent from a particular country, then specific draft import conditions will be proposed for small corm taro from that country.

Review of import conditions for fresh taro corms Introduction

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1 Introduction

1.1 Australia’s biosecurity policy framework Australia’s biosecurity policies aim to protect Australia against the risks that may arise from exotic pests1 entering, establishing and spreading in Australia, thereby threatening Australia’s unique flora and fauna, as well as those agricultural industries that are relatively free from serious pests.

The pest risk analysis (PRA) process is an important part of Australia’s biosecurity policies. It enables the Australian Government to formally consider the risks that could be associated with proposals to import new products into Australia. If the risks are found to exceed Australia’s appropriate level of protection (ALOP), risk management measures are proposed to reduce the risks to an acceptable level. However, if it is not possible to reduce the risks to an acceptable level, then no trade will be allowed.

Successive Australian Governments have maintained a conservative, but not a zero-risk, approach to the management of biosecurity risks. This approach is expressed in terms of Australia’s ALOP, which reflects community expectations through government policy and is currently described as providing a high level of protection aimed at reducing risk to a very low level, but not to zero.

Australia’s PRAs are undertaken by Biosecurity Australia using teams of technical and scientific experts in relevant fields, and involve consultation with stakeholders at various stages during the process. The Australian Quarantine and Inspection Service (AQIS) is responsible for implementing appropriate risk management measures.

More information about Australia’s biosecurity framework is provided in Appendix C of this report and in the Import Risk Analysis Handbook 2007 located on the Biosecurity Australia website http://www.daff.gov.au/ba.

1.2 This import risk analysis

1.2.1 Background

Quarantine policy for the importation of fresh taro (Colocasia esculenta (L.) Schott.) corms into Australia for human consumption has been in place for many years.

In June 2003, following a review of the existing import conditions for taro corms, Biosecurity Australia advised AQIS that taro corms should continue to meet the general conditions for fruit and vegetables, as well as being topped and free of leaf material.

In June 2005, Taro Growers Australia wrote to AQIS expressing concerns about the import conditions for fresh taro corms and claimed that its members had seen imported taro corms in breach of these conditions. Further correspondence between Taro Growers Australia and Biosecurity Australia in 2006 discussed the quarantine risk from imports of corms of the

1 A pest is any species, strain or biotype of plant, animal, or pathogenic agent injurious to plants or plant products (FAO 2009)


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small corm taro (Colocasia esculenta var. antiquorum) that propagate easily from multiple growing points, even after the removal of the apical growing point.

In response to the concerns that corms of the small corm taro can be readily propagated, Biosecurity Australia advised AQIS in May 2006 that small corm taro should no longer be permitted entry, and this advice was applied from 23 May 2006. From 7 July 2006, phytosanitary certificates were required to carry an additional declaration that the consignment was not Colocasia esculenta var. antiquorum. A notification (G/SPS/N/AUS/199: 06/3352) of the emergency measure to halt imports of Colocasia esculenta var. antiquorum to Australia was made to the World Trade Organization (WTO) on 11 July 2006.

Subsequently, Taro Growers Australia claimed that small corm taro was being imported labelled as the large corm variety. In November 2006, Biosecurity Australia recommended to AQIS that size and morphological criteria be adopted and used by inspectors to distinguish the two varieties. These criteria were adopted on 1 December 2006, and notification (G/SPS/N/AUS/199/Rev.1: 06/5810) of the modification to the emergency measure was made to the WTO on 4 December 2006.

To meet its obligations under the WTO Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement), Australia is required to investigate the phytosanitary situation where emergency actions are taken to determine whether the actions are justified, in accordance with the International Plant Protection Convention (IPPC) and the International Standards for Phytosanitary Measures (ISPMs). This review was initiated in response to stakeholder concerns and the subsequent adoption of emergency measures.

1.2.2 Scope

This review of import conditions assesses the biosecurity risks associated with the importation of fresh taro corms from all countries for human consumption. It considers both the large and small corm varieties.

In the PRA section of this report, Biosecurity Australia has considered the pests associated with taro corms. The assessment of unrestricted risk is based on the importation of commercially produced taro corms from all countries into Australia as described in Section 3.

This final report does not consider the risks associated with the importation of taro corms as planting material specifically for propagation purposes on a commercial scale. The intentional importation of fresh taro for the purpose of propagation (for example, by farmers) under an import permit for human consumption is a breach of import conditions, and liable to prosecution under the Quarantine Act 1908. The report does, however, take into account the possibility that consumers could potentially attempt to plant corms purchased from retail markets, as this pathway cannot be effectively regulated. It is expected that volumes of taro diverted to growing purposes by consumers would be small.

A new pathogen, Marasmiellus colocasiae, recently reported from Brazil was not assessed in the draft report. At present there is insufficient relevant scientific evidence available to undertake a risk assessment of this disease. There are currently no imports of taro from Brazil into Australia. In the interests of expediting the assessment of risk from those countries currently exporting taro to Australia, the scope of this assessment has been revised to exclude countries where Marasmiellus colocasiae has been reported. The assessment of risk and the


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need for phytosanitary measures will be reviewed if an intent to trade is demonstrated and additional information becomes available.

Regional pest freedoms are not considered in the pest categorisation process where there are no specific management measures applied to interstate movement of taro exceeding the AQIS standard operational requirements for clearance of fresh produce (i.e. inspection, free of soil). Consistent with obligations under the SPS Agreement, Australia must apply phytosanitary measures without discrimination between domestic and imported consignments.

In addition to fresh taro corms, there is a small market in Australia for fresh taro leaves, used in traditional cooking practices. Consideration of this commodity is outside the scope of this review.

1.2.3 Existing policy

Prior to the introduction of emergency measures in 2006 prohibiting the importation of small corm taro, Australia permitted the importation of fresh corms of Colocasia esculenta (including var. antiquorum) for human consumption from all countries, subject to specific import conditions. These import conditions included:

• topping to remove all petiole bases, the apical growing point and all foliage

• on-arrival inspection for quarantine pests and other regulated articles (e.g. soil, trash and seeds).

Following the prohibition of small corm taro imports in 2006, a further condition was added to require that imported corms meet specific morphological criteria to ensure corms of Colocasia esculenta var. antiquorum do not gain entry. Specifically the corms must:

• be at least 15 cm long or be at least 7 cm in diameter at the widest point

• be at least 300 g in weight

• be free of lateral buds or shoots

• lack shaggy hairs.

This review proposes changes to the existing import conditions for fresh taro corms to address identified quarantine risks.

1.2.4 Contaminating pests

In addition to the pests of taro identified in this pest risk analysis, there are other organisms that may arrive with the corms. These organisms could include weed seeds, pests of other crops, or predators and parasitoids of other arthropods. Biosecurity Australia considers these organisms as contaminant pests that could pose sanitary and phytosanitary risks. These risks are addressed by existing AQIS standard operational procedures.

1.2.5 Consultation

The draft report was released on 16 March 2011 (BAA 2011/02) for comment and consultation with stakeholders, for a period of 60 days that concluded on 20 May 2011. Written submissions were received from seventeen stakeholders. Submissions have been considered and material matters raised have been included in the present report. Biosecurity


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Australia also consulted informally with various stakeholders, including Taro Growers Australia and the Biosecurity Authority of Fiji, during the preparation of the final report.

Following stakeholder consultation, some amendments have been made to the final report.

• Twelve new pests have been added to the categorisation table.

• An additional pest risk assessment has been included for the yam scale, Aspidiella hartii. • For spiral nematodes, the rating for probability of distribution has been raised from ‘Low’

to ‘Moderate’, and probability of spread raised from ‘Moderate’ to ‘High’. The resulting unrestricted risk estimate is ‘Very low’, which is still below ALOP and does not require application of additional measures.

• The rating for potential establishment of the French Polynesian strain of Dasheen mosaic virus has been raised from ‘Moderate’ to ‘High’, bringing the unrestricted risk estimate to ‘Low’, which is above ALOP, thereby requiring management measures to mitigate the quarantine risk.

• The fungal pathogen Marasmiellus colocasiae, responsible for corm rot, has been identified through the categorisation process, but not enough information is currently available to adequately assess the quarantine risks. Consequently, imports of taro from Brazil and any other country where this pathogen is known to occur will not be permitted.

1.2.6 Next steps

Biosecurity Australia will advise AQIS on the recommended pest risk management measures.

Countries that wish to propose alternative measures to mitigate the quarantine risks associated with taro leaf blight, or consideration of market access for small corm taro, will need to submit formal applications to Biosecurity Australia.

Review of import conditions for fresh taro corms Method for PRA

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2 Method for pest risk analysis

This section sets out the method used for the pest risk analysis (PRA) in this report. Biosecurity Australia has conducted this PRA in accordance with the International Standards for Phytosanitary Measures (ISPMs), including ISPM 2: Framework for pest risk analysis (FAO 2007) and ISPM 11: Pest risk analysis for quarantine pests, including analysis of environmental risks and living modified organisms (FAO 2004).

A PRA is ‘the process of evaluating biological or other scientific and economic evidence to determine whether a pest should be regulated and the strength of any phytosanitary measures to be taken against it’ (FAO 2010). A pest is ‘any species, strain or biotype of plant, animal, or pathogenic agent injurious to plants or plant products’ (FAO2010).

Quarantine risk consists of two major components: the probability of a pest entering, establishing and spreading in Australia from imports, and the consequences should this happen. These two components are combined to give an overall estimate of the risk.

Unrestricted risk is estimated taking into account the existing commercial production practices of the exporting country and that, on arrival in Australia, AQIS will verify that the consignment received is as described on the commercial documents and its integrity has been maintained.

Restricted risk is estimated with phytosanitary measure(s) applied. A phytosanitary measure is ‘any legislation, regulation or official procedure having the purpose to prevent the introduction and spread of quarantine pests, or to limit the economic impact of regulated non-quarantine pests’ (FAO 2010).

A glossary of the terms used is provided at the back of this report.

The PRA was conducted in the following three consecutive stages.

2.1 Stage 1: Initiation Initiation identifies the pest(s) and pathway(s) that are of quarantine concern and should be considered for risk analysis in relation to the identified PRA area.

The initiation point for this PRA was the adoption of emergency measures prohibiting imports of small corm taro (Colocasia esculenta var. antiquorum) in 2006. This followed concerns that small corm taro was unaffected by topping and could be propagated. Having adopted emergency measures, Australia is obliged under the SPS Agreement to undertake a scientific review of the risks and phytosanitary measures (Article 5, Clause 7) in accordance with ISPM 13 (FAO 2001a). This review was undertaken to meet this requirement.

The pests associated with taro plants and corms were tabulated from literature and database searches. This information is set out in Appendix A. The species name is used in most instances but a lower taxonomic level is used where appropriate. Synonyms are provided where the cited literature uses a different scientific name.

For this PRA, the ‘PRA area’ is defined as Australia for pests that are absent, or of limited distribution and under official control. For areas with regional freedom from a pest, the ‘PRA area’ may be defined on the basis of a state or territory of Australia or may be defined as a region of Australia consisting of parts of a state or territory or several states or territories


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2.2 Stage 2: Pest risk assessment A pest risk assessment (for quarantine pests) is: ‘the evaluation of the probability of the introduction and spread of a pest and of the likelihood of associated potential economic consequences’ (FAO 2010).

In this PRA, pest risk assessment was divided into the following interrelated processes:

2.2.1 Pest categorisation

Pest categorisation identifies which of the pests with the potential to be on the commodity are quarantine pests for Australia and require pest risk assessment. A ‘quarantine pest’ is a pest of potential economic importance to the area endangered thereby and not yet present there, or present but not widely distributed and being officially controlled, as defined in ISPM 5: Glossary of phytosanitary terms (FAO 2010).

The pests identified in Stage 1 were categorised using the following primary elements to identify the quarantine pests for the commodity being assessed: • presence or absence in the PRA area • regulatory status • potential for establishment and spread in the PRA area • potential for economic consequences (including environmental consequences) in the PRA

area.

The results of pest categorisation are set out in Appendix A. The quarantine pests identified during pest categorisation were carried forward for pest risk assessment and are listed in Table 4.1.

2.2.2 Assessment of the probability of entry, establishment and spread

Details of how to assess the ‘probability of entry’, ‘probability of establishment’ and ‘probability of spread’ of a pest are given in ISPM 11 (FAO 2004). A summary of this process is given below, followed by a description of the qualitative methodology used in this PRA.

Probability of entry

The probability of entry describes the probability that a quarantine pest will enter Australia as a result of trade in a given commodity, be distributed in a viable state in the PRA area and subsequently be transferred to a host. It is based on pathway scenarios depicting necessary steps in the sourcing of the commodity for export, its processing, transport and storage, its use in Australia and the generation and disposal of waste. In particular, the ability of the pest to survive is considered for each of these stages.

The probability of entry estimates for the quarantine pests associated with a commodity are based on the use of the existing commercial production, packaging and shipping practices of the exporting country or countries. Details of the existing commercial production practices for the commodity are set out in Section 3. These practices are taken into consideration by Biosecurity Australia when estimating the probability of entry.


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For the purpose of considering the probability of entry, Biosecurity Australia divides this step of this stage of the PRA into two components:

• Probability of importation: the probability that a pest will arrive in Australia when a given commodity is imported.

• Probability of distribution: the probability that the pest will be distributed, as a result of the processing, sale or disposal of the commodity in the PRA area and subsequently transfer to a susceptible part of a host.

Factors considered in the probability of importation include: • distribution and incidence of the pest in the source area • occurrence of the pest in a life-stage that would be associated with the commodity • volume and frequency of movement of the commodity along each pathway • seasonal timing of imports • pest management, cultural and commercial procedures applied at the place of origin • speed of transport and conditions of storage compared with the duration of the lifecycle

of the pest • vulnerability of the life-stages of the pest during transport or storage • incidence of the pest likely to be associated with a consignment • commercial procedures (e.g. refrigeration) applied to consignments during transport and

storage in the country of origin, and during transport to Australia.

Factors considered in the probability of distribution include: • commercial procedures (e.g. refrigeration) applied to consignments during distribution in

Australia • dispersal mechanisms of the pest, including vectors, to allow movement from the

pathway to a host • whether the imported commodity is to be sent to a few or many destination points in the

PRA area • proximity of entry, transit and destination points to hosts • time of year at which import takes place • intended use of the commodity (e.g. for planting, processing or consumption) • risks from by-products and waste.

Probability of establishment

Establishment is defined as the ‘perpetuation for the foreseeable future, of a pest within an area after entry’ (FAO 2010). In order to estimate the probability of establishment of a pest, reliable biological information (life cycle, host range, epidemiology, survival, etc.) is obtained from the areas where the pest currently occurs. The situation in the PRA area can then be compared with that in the areas where it currently occurs and expert judgement used to assess the probability of establishment.

Factors considered in the probability of establishment in the PRA area include: • availability of hosts, alternative hosts and vectors • suitability of the environment • reproductive strategy and potential for adaptation


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• minimum population needed for establishment • cultural practices and control measures.

Probability of spread

Spread is defined as ‘the expansion of the geographical distribution of a pest within an area’ (FAO 2010). The probability of spread considers the factors relevant to the movement of the pest, after establishment on a host plant or plants, to other susceptible host plants of the same or different species in other areas. In order to estimate the probability of spread of the pest, reliable biological information is obtained from areas where the pest currently occurs. The situation in the PRA area is then carefully compared with that in the areas where the pest currently occurs and expert judgement used to assess the probability of spread.

Factors considered in the probability of spread include: • suitability of the natural and/or managed environment for natural spread of the pest • presence of natural barriers • the potential for movement with commodities, conveyances or by vectors • intended use of the commodity • potential vectors of the pest in the PRA area • potential natural enemies of the pest in the PRA area.

Assigning qualitative likelihoods for the probability of entry, establishment and spread

In its qualitative PRAs, Biosecurity Australia uses the term ‘likelihood’ for the descriptors it uses for its estimates of probability of entry, establishment and spread. Qualitative likelihoods are assigned to each step of entry, establishment and spread. Six descriptors are used: high, moderate, low, very low, extremely low and negligible. Descriptive definitions for these descriptors and their indicative probability ranges are given in Table 2.1. The indicative probability ranges are only provided to illustrate the boundaries of the descriptors. These indicative probability ranges are not used beyond this purpose in qualitative PRAs. The standardised likelihood descriptors and the associated indicative probability ranges provide guidance to the risk analyst and promote consistency between different risk analyses.

Table 2.1: Nomenclature for qualitative likelihoods

Likelihood Descriptive definition Indicative probability (P) range

High The event would be very likely to occur 0.7 < P ≤ 1

Moderate The event would occur with an even probability 0.3 < P ≤ 0.7

Low The event would be unlikely to occur 0.05 < P ≤ 0.3

Very low The event would be very unlikely to occur 0.001 < P ≤ 0.05

Extremely low The event would be extremely unlikely to occur 0.000001 < P ≤ 0.001

Negligible The event would almost certainly not occur 0 ≤ P ≤ 0.000001

The likelihood of entry is determined by combining the likelihood that the pest will be imported into the PRA area and the likelihood that the pest will be distributed within the PRA area, using a matrix of rules (Table 2.2). This matrix is then used to combine the likelihood of entry and the likelihood of establishment, and the likelihood of entry and establishment is


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then combined with the likelihood of spread to determine the overall likelihood of entry, establishment and spread.

For example, if the probability of importation is assigned a likelihood of ‘low’ and the probability of distribution is assigned a likelihood of ‘moderate’, then they are combined to give a likelihood of ‘low’ for the probability of entry. The likelihood for the probability of entry is then combined with the likelihood assigned to the probability of establishment (e.g. ‘high’) to give a likelihood for the probability of entry and establishment of ‘low’. The likelihood for the probability of entry and establishment is then combined with the likelihood assigned to the probability of spread (e.g. ‘very low’) to give the overall likelihood for the probability of entry, establishment and spread of ‘very low’.

Table 2.2: Matrix of rules for combining qualitative likelihoods

High Moderate Low Very low Extremely low Negligible

High High Moderate Low Very low Extremely low Negligible

Moderate Low Low Very low Extremely low Negligible

Low Very low Very low Extremely low Negligible

Very low Extremely low Extremely low Negligible

Extremely low Negligible Negligible

Negligible Negligible

Time and volume of trade

One factor affecting the likelihood of entry is the volume and duration of trade. If all other conditions remain the same, the overall likelihood of entry will increase as time passes and the overall volume of trade increases.

Biosecurity Australia normally considers the likelihood of entry on the basis of the estimated volume of one year’s trade. This is a convenient value for the analysis that is relatively easy to estimate and allows for expert consideration of seasonal variations in pest presence, incidence and behaviour to be taken into account. The consideration of the likelihood of entry, establishment and spread and subsequent consequences takes into account events that might happen over a number of years even though only one year’s volume of trade is being considered. This difference reflects biological and ecological facts, for example where a pest or disease may establish in the year of import but spread may take many years.

The use of a one year volume of trade has been taken into account when setting up the matrix that is used to estimate the risk and therefore any policy based on this analysis does not simply apply to one year of trade. Policy decisions that are based on Biosecurity Australia’s method that uses the estimated volume of one year’s trade are consistent with Australia’s policy on appropriate level of protection and meet the Australian Government’s requirement for ongoing quarantine protection. Of course, if there are substantial changes in the volume and nature of the trade in specific commodities then Biosecurity Australia has an obligation to review the risk analysis and, if necessary, provide updated policy advice.

In assessing the volume of trade in this PRA, Biosecurity Australia assumed that a substantial volume of trade will occur.


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2.2.3 Assessment of potential consequences

The objective of the consequence assessment is to provide a structured and transparent analysis of the likely consequences if the pests or disease agents were to enter, establish and spread in Australia. The assessment considers direct and indirect pest effects and their economic and environmental consequences. The requirements for assessing potential consequences are given in Article 5.3 of the SPS Agreement (WTO 1995), ISPM 5 (FAO 2010) and ISPM 11 (FAO 2004).

Direct pest effects are considered in the context of the effects on: • plant life or health • other aspects of the environment.

Indirect pest effects are considered in the context of the effects on: • eradication, control, etc. • domestic trade • international trade • environment.

For each of these six criteria, the consequences were estimated over four geographic levels, defined as:

• Local: an aggregate of households or enterprises (a rural community, a town or a local government area).

• District: a geographically or geopolitically associated collection of aggregates (generally a recognised section of a state or territory, such as ‘Far North Queensland’).

• Regional: a geographically or geopolitically associated collection of districts in a geographic area (generally a state or territory, although there may be exceptions with larger states such as Western Australia).

• National: Australia wide (Australian mainland states and territories and Tasmania).

For each criterion, the magnitude of the potential consequence at each of these levels was described using four categories, defined as:

• Indiscernible: Pest impact unlikely to be noticeable.

• Minor significance: Expected to lead to a minor increase in mortality/morbidity of hosts or a minor decrease in production but not expected to threaten the economic viability of production. Expected to decrease the value of non-commercial criteria but not threaten the criterion’s intrinsic value. Effects would generally be reversible.

• Significant: Expected to threaten the economic viability of production through a moderate increase in mortality/morbidity of hosts, or a moderate decrease in production. Expected to significantly diminish or threaten the intrinsic value of non-commercial criteria. Effects may not be reversible.

• Major significance: Expected to threaten the economic viability through a large increase in mortality/morbidity of hosts, or a large decrease in production. Expected to severely or irreversibly damage the intrinsic ‘value’ of non-commercial criteria.


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The estimates of the magnitude of the potential consequences over the four geographic levels were translated into a qualitative impact score (A–G)2 using Table 2.33. For example, a consequence with a magnitude of ‘significant’ at the ‘district’ level will have a consequence impact score of D.

Table 2.3 Decision rules for determining the consequence impact score based on the magnitude of consequences at four geographic scales

Geographic scale

Local District Region Nation

Mag

nitu

de Indiscernible A A A A

Minor significance B C D E

Significant C D E F

Major significance D E F G

The overall consequence for each pest is achieved by combining the qualitative impact scores (A–G) for each direct and indirect consequence using a series of decision rules (Table 2.4). These rules are mutually exclusive, and are assessed in numerical order until one applies.

Table 2.4: Decision rules for determining the overall consequence rating for each pest

Rule The impact scores for consequences of direct and indirect criteria Overall consequence rating

1 Any criterion has an impact of ‘G’; or more than one criterion has an impact of ‘F’; or a single criterion has an impact of ‘F’ and each remaining criterion an ‘E’.

Extreme

2 A single criterion has an impact of ‘F’; or all criteria have an impact of ‘E’.

High

3 One or more criteria have an impact of ‘E’; or all criteria have an impact of ‘D’.

Moderate

4 One or more criteria have an impact of ‘D’; or all criteria have an impact of ‘C’.

Low

5 One or more criteria have an impact of ‘C’; or all criteria have an impact of ‘B’.

Very Low

6 One or more but not all criteria have an impact of ‘B’, and all remaining criteria have an impact of ‘A’.

Negligible

2.2.4 Estimation of the unrestricted risk

Once the above assessments are completed, the unrestricted risk can be determined for each pest or groups of pests. This is determined by using a risk estimation matrix (Table 2.5) to combine the estimates of the probability of entry, establishment and spread and the overall

2 In earlier qualitative IRAs, the scale for the impact scores went from A to F and did not explicitly allow for the rating ‘indiscernible’ at all four levels. This combination might be applicable for some criteria. In this report, the impact scale of A-F has changed to become B-G and a new lowest category A (‘indiscernible’ at all four levels) was added. The rules for combining impacts in Table 2.4 were adjusted accordingly. 3 The decision rules for determining the consequence impact score are presented in a simpler form in Table 2.3 from earlier IRAs, to make the table easier to use. The outcome of the decision rules is the same as the previous table and makes no difference to the final impact score.


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consequences of pest establishment and spread. Therefore, risk is the product of likelihood and consequence.

When interpreting the risk estimation matrix, note the descriptors for each axis are similar (e.g. low, moderate, high) but the vertical axis refers to likelihood and the horizontal axis refers to consequences. Accordingly, a ‘low’ likelihood combined with ‘high’ consequences, is not the same as a ‘high’ likelihood combined with ‘low’ consequences – the matrix is not symmetrical. For example, the former combination would give an unrestricted risk rating of ‘moderate’, whereas, the latter would be rated as a ‘low’ unrestricted risk.

Table 2.5: Risk estimation matrix

Like

lihoo

d of

pes

t ent

ry, e

stab

lishm

ent

and

spre

ad

High Negligible risk

Very low risk Low risk Moderate risk High risk Extreme risk

Moderate Negligible risk

Very low risk Low risk Moderate risk High risk Extreme risk

Low Negligible risk

Negligible risk

Very low risk Low risk Moderate risk High risk

Very low Negligible risk

Negligible risk

Negligible risk

Very low risk Low risk Moderate risk

Extremely low

Negligible risk

Negligible risk

Negligible risk

Negligible risk

Very low risk Low risk

Negligible Negligible risk

Negligible risk

Negligible risk

Negligible risk

Negligible risk

Very low risk

Negligible Very low Low Moderate High Extreme

Consequences of pest entry, establishment and spread

2.2.5 Australia’s appropriate level of protection (ALOP)

The SPS Agreement defines the concept of an ‘appropriate level of sanitary or phytosanitary protection (ALOP)’ as the level of protection deemed appropriate by the WTO Member establishing a sanitary or phytosanitary measure to protect human, animal or plant life or health within its territory.

Like many other countries, Australia expresses its ALOP in qualitative terms. Australia’s ALOP, which reflects community expectations through government policy, is currently expressed as providing a high level of sanitary or phytosanitary protection aimed at reducing risk to a very low level, but not to zero. The band of cells in Table 2.5 marked ‘very low risk’ represents Australia’s ALOP.

2.3 Stage 3: Pest risk management Pest risk management describes the process of identifying and implementing phytosanitary measures to manage risks to achieve Australia's ALOP, while ensuring that any negative effects on trade are minimised.

The conclusions from the pest risk assessment are used to decide whether risk management is required and if so, the appropriate measures to be used. Where the unrestricted risk estimate exceeds Australia’s ALOP, risk management measures are required to reduce this risk to a very low level. The guiding principle for risk management is to manage risk to achieve


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Australia’s ALOP. The effectiveness of any proposed phytosanitary measure (or combination of measures) is evaluated, using the same approach as used to evaluate the unrestricted risk, to ensure it reduces the restricted risk for the relevant pest or pests to meet Australia’s ALOP.

ISPM 11 (FAO 2004) provides details on the identification and selection of appropriate risk management options and notes that the choice of measures should be based on their effectiveness in reducing the probability of entry of the pest.

Examples given of measures commonly applied to traded commodities include:

• options for consignments – e.g., inspection or testing for freedom from pests, prohibition of parts of the host, a pre-entry or post-entry quarantine system, specified conditions on preparation of the consignment, specified treatment of the consignment, restrictions on end-use, distribution and periods of entry of the commodity

• options preventing or reducing infestation in the crop – e.g., treatment of the crop, restriction on the composition of a consignment so it is composed of plants belonging to resistant or less susceptible species, harvesting of plants at a certain age or specified time of the year, or production in a certification scheme

• options ensuring that the area, place or site of production or crop is free from the pest – e.g., pest-free area, pest-free place of production or pest-free production site

• options for other types of pathways – e.g., consider natural spread, measures for human travellers and their baggage, cleaning or disinfestation of contaminated machinery

• options within the importing country – e.g., surveillance and eradication programs

• prohibition of commodities – if no satisfactory measure can be found.

Risk management measures are identified for each quarantine pest where the risk exceeds Australia’s ALOP. These are presented in the ‘Pest risk management’ section of this report.

Review of import conditions for fresh taro corms Commercial taro production and trade

15

3 Commercial taro production and trade

3.1 Assumptions used to estimate unrestricted risk Biosecurity Australia took into consideration the following information on commercial production practices when estimating the unrestricted risk of pests likely to be associated with fresh taro corms. Additional information on taro varieties is presented in Appendix D.

Large corm taro (Colocasia esculenta var. esculenta) is traditionally marketed with a short tuft of petiole bases attached, but with most of the leaf material removed. This protects the apical meristem to ensure the corm stays physiologically active, which delays the development of storage rots. The roots and soil are also removed from the corms during harvest or at the packing house. The corm of this variety is large and cylindrical, up to 30 cm in length and 15 cm in diameter, lacking hairs, with few cormels (stem tubers). The central corm is harvested as the main crop, with the lateral cormels being removed and discarded or used as planting stock.

Estimates of the unrestricted risk assume that the petiole bases are present on corms of the large corm variety. The quality control of the removal of leaves and roots may vary, so it is assumed that occasionally a small number of corms with a few minor stems or roots may be packed for export. During transport and storage, the feeder roots desiccate and the outer parts of the corm begin to dry out, affecting the feeding of external pests such as root aphids and nematodes.

Existing import conditions for large corm taro in Australia require topping to remove all petiole bases and the apical growing points to prevent the corms being propagated. If the petiole bases and the apical growing points are excised, the remaining lateral buds on the corm will usually not sprout. This topping is an additional quarantine measure, and is not considered when assessing the unrestricted risk.

Fresh corms of the small corm type (Colocasia esculenta var. antiquorum) are not currently permitted entry to Australia, following the introduction of emergency measures in 2006. The central corm of this variety is small, globoid, and surrounded by cormels (daughter corms). The harvested crop is actually the lateral cormels and daughter corms, as the central corm is generally considered inedible. Removal of the apical growing point does not affect the propagability of small corm taro. After the apex has been removed, these daughter corms will still sprout readily from lateral buds in the corm, and so may be propagated easily. The potential propagation of small corm taro is considered when assessing the unrestricted risk.

See Figures D.1 and D.2 in Appendix D for diagrams identifying the key features that differentiate the corms of the large and small corm varieties of taro.

Estimates of the unrestricted risk in this report assume that soil has been removed from the corms during harvest and grading operations.

3.2 Taro cultivation practices Taro is an adaptable crop that tolerates flooding, salinity and shading. Cultivation practices vary from region to region. Detailed accounts of cultivation practices in countries of Asia and Oceania are given in Wilson and Siemonsma (1996), Onwueme (1999) and Vinning (2003).


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Propagation is almost entirely by vegetative means, with four types of planting material used (Onwueme 1999):

• side suckers from the harvested crop used directly or sprouted under nursery conditions

• small corms from the harvested crop used directly or sprouted under nursery conditions

• headsetts of large corm taro (the apical 1–2 cm of the corm with the basal 15–20 cm of the petiole bases attached), which are planted straight after harvest

• corm pieces of small corm taro, around 30–50 g in weight, either planted directly, or sprouted under nursery conditions.

Seeds are rarely available, and when planted exhibit phenotypic variability. Meristem tissue culture is used to bulk-up elite clones, but is not used routinely to produce planting material.

Two main production systems are used in the Asia and Oceania regions: flooded or wetland production, and dryland or upland production. Cropping densities range from 4000 to 49 000 plants per hectare. In SE Asia, densities of 6000 to 36 000 plants/ha in dryland cropping and 27 000 to 40 000 plants/ha in flooded cropping are usual.

Flooded taro production utilises a paddy system similar to that for rice. It requires a heavy soil and cool running water (warm or stagnant water can lead to corm rot). Either irrigation or diversion/adaptation of natural rivers, streams or swamps may be used. After establishment of an impoundment area, the ground is flooded just before or just after planting. The water level is gradually raised during growth so that the base of the plant is always under water. If water is drained for fertilising, it is raised again within a few days. Maturity is reached in 12–15 months.

The advantages of flooded production are higher corm yields (about double) and minimal weed infestation, and year-round production is possible. Disadvantages are the high infrastructure and operational costs, a longer time to maturity, and increased susceptibility to root and corm rots, particularly if water is stagnant. Intercropping is usually not possible.

Dryland taro is grown in fields and relies mainly on rainfall. Sometimes minimal furrow or sprinkler irrigation is used, designed to keep the soil moist but not flooded. The rainy season must last 6–9 months and deliver 2500 mm of rainfall unless supplemented by irrigation. Planting is on the flat, or on ridges 70–100 cm apart. Intercropping between coconut and oil palms, fruit trees, coffee or cocoa is common. Mulching is necessary, as is weed control during the first three months until the canopy closes. Maturity is reached in 5–12 months.

Advantages are faster maturity, lower investment in infrastructure and operational costs, lower incidence of root and corm rots, and production is not dependent on large quantities of water. Disadvantages are that the planting time is dictated by the onset of the rainy season, it results in lower yields and weeding is necessary during the first three months.

3.3 The global taro industry Food and Agriculture Organization of the United Nations (FAO) estimates for taro production in 2009 (FAO 2011) are shown in Table 3.1. Although the major taro-producing countries are in Africa and Asia, taro forms a relatively small part of the diet there. In the Pacific, however, taro is a staple, particularly in the Cook Islands, Fiji, Futuna, Niue, Samoa, Tahiti, Tonga and Micronesia (Vinning 2003).


17

Table 3.1: Estimated production of taro in 2009 from the 20 highest producers worldwide (FAO 2011)

Country Production (tonnes)

Country Production (tonnes)

Nigeria 4 459 650 Central African Republic 113 667

China 1 692 551 Thailand 104 472

Cameroon 1 668 130 Côte d’Ivoire 90 000

Ghana 1 504 000 Gabon 70 131

Papua New Guinea 313 814 Fiji 69 863

Madagascar 239 901 Democratic Republic of Congo 65 000

Japan 182 000 Solomon Islands 48 449

Egypt 160 000 Burundi 44 502

Rwanda 136 849 Sao Tome and Principe 35 066

Philippines 120 000 Chad 32 732

World trade in taro is estimated at about 145 000 tonnes per annum (Vinning 2003), largely based on supplying expatriate populations (Pacific Islanders, Hispanics and Chinese) with a traditional staple. The exception is Japan, where imports are consumed largely by the indigenous population. Export statistics for the major taro exporting countries in 2008 are listed in Table 3.2.

Table 3.2: Top taro exporting countries in 2008 (FAO 2011)

Country Quantity (tonnes) China 49 118

Fiji 11 114

United States of America 7107

Costa Rica 6738

Dominica 618

Samoa 199

Tonga 103

3.3.1 The Australian taro industry

Taro is produced commercially in New South Wales, Queensland and the Northern Territory. Traditionally it was grown as a domestic garden crop and used and traded by the growers through an informal system. Taro is grown all year round in the northern parts of Australia.

It is estimated that more than 1000 tonnes of taro is produced commercially in Australia each year, and more than 3000 tonnes of taro is imported (Daniells et al. 2004; Vinning 2003). Very little of the commercially grown and imported taro is processed. More than two million fresh taro corms are likely to be traded and consumed domestically each year.


18

Estimates of the size of the Australian market vary widely, but most support the idea that the size of the market is expanding. Production in Australia is expected to increase because of the influx of new growers, stable prices, demand exceeding supply, opportunities for import replacement and the development of new products such as taro chips (Horsburgh and Noller 2005).

Review of import conditions for fresh taro corms Pest risk assessments

19

4 Pest risk assessments for quarantine pests

4.1 Quarantine pests for pest risk assessment Pest categorisation (Appendix A) identified 33 quarantine pests associated with fresh taro corms from all countries in this PRA (Table 4.1).

Table 4.1: Quarantine pests for fresh taro corms from all countries

Pest Common name Weevils [Coleoptera: Circulionoidea] Elytroteinus subtruncatus (Fairmaîre, 1881) Fiji ginger weevil Beetles [Coleoptera: Scarabaeidae] Eucopidocaulus tridentipes (Arrow, 1911)

Taro beetles

Papuana biroi (Endrödi, 1969) Papuana cheesmanae Arrow, 1941 Papuana huebneri Fairmaîre, 1879 Papuana inermis Prell, 1912 Papuana japenensis Arrow, 1941 Papuana laevipennis Arrow, 1911 Papuana semistriata Arrow, 1911 Papuana szentivanyi (Endrödi, 1971) Papuana trinodosa Prell, 1912 Papuana uninodis Prell, 1912 Planthoppers [Hemiptera: Delphacidae] Tarophagus proserpina (Kirkaldy, 1907) Taro planthopper Scales [Hemiptera: Diaspididae] Aspidiella hartii (Cockerell, 1895) Yam scale Mealybugs [Hemiptera: Pseudococcidae] Paraputo aracearum Williams, 2005

Mealybugs Paraputo leveri (Green, 1934) Aphids [Hemiptera: Pemphigidae] Patchiella reaumuri (Kaltenbach, 1843) Taro root aphid Nematodes Helicotylenchus microcephalus Sher, 1966

Spiral nematodes Helicotylenchus mucronatus Siddiqi, 1963 Hirschmanniella miticausa Bridge, Mortimer & Jackson, 1983 Taro root nematode Longidorus sylphus Thorne, 1939 Needle nematode Bacteria Xanthomonas axonopodis pv. dieffenbachiae (McCulloch & Pirone, 1939) Vauterin et al., 1995 Bacterial blight of taro

Fungi Corallomycetella repens (Berkeley & Broome) Rossman & Samuels Corallomycetella root rot

Marasmiellus colocasiae Capelari & Antonín Corm rot Rosellinia pepo Patouillard Black root rot Straminopila Phytophthora colocasiae Raciborski Taro leaf blight


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Pest Common name Phytophthora sp. Taro pocket rot Pythium carolinianum V.D. Matthews Pythium corm rot Viruses colocasia bobone disease virus (CBDV) Colocasia bobone disease French Polynesian strain of Dasheen mosaic virus (FP-DsMV) French Polynesian strain of dasheen mosaic taro reovirus (TaRV) Taro vein chlorosis virus (TaVCV) Taro vein chlorosis tomato zonate spot virus (TZSV) Tomato zonate spot

Pest risk assessments for these quarantine pests are presented in this section. The results of these pest risk assessments are summarised in Table 4.2, together with the overall restricted risk estimates. The rationale for each value in the pest risk assessments is described in the relevant sections below.

Review of import conditions for fresh taro corms Pest risk assessment – Fiji ginger weevil

21

4.2 Fiji ginger weevil Elytroteinus subtruncatus Very little is known of the developmental biology of Elytroteinus subtruncatus because it is difficult to rear under laboratory conditions (Mau and Martin Kessing 1992a). The adult lays a single egg in corms, tubers, fruits or soft stems of a range of plants. The larva bores through the tissues, completing its development inside the plant. Elytroteinus subtruncatus is associated with a diverse range of plant hosts, including taro corms, ginger (Zingiber officinale) rhizomes, avocado (Persea americana) seeds, daylily (Hemerocallis spp.) stems, kava (Piper methysticum) stems, cycad (Cycas spp.) trunks, ti (Cordyline fruticosa) cuttings, lemons (Citrus limon), dwarf mondo (Ophiopogon japonicus) roots, Marrattia fern trunks and dead sugarcane (Saccharum spp.) (Follett et al. 2007; Mau and Martin Kessing 1992a).

Elytroteinus subtruncatus is endemic to a small number of countries in the South Pacific. It is also present in Hawaii and may have been introduced there. It first came to attention as a pest in the 1910s and 1920s (Miller 1923; Simmonds 1928). Recent references are scarce, suggesting that it is not a major concern. However, the weevil was considered a serious pest in Tonga, where it was reported attacking stems of kava (Fakalata 1981).

In the United States of America (USA), the Animal and Plant Health Inspection Service (APHIS) considers Elytroteinus subtruncatus to be a high-risk pest requiring mitigation for sweet potatoes exported from Hawaii to the mainland. This is the result of five weevil interceptions in 1995 and 1997 (nine sweet potato roots containing a total of eight larvae and two pupae) found in passenger baggage at Keahole International Airport, Hawaii (Follett et al. 2007). However, sweet potato is not reported in the literature as a host of Elytroteinus subtruncatus. The weevil has never been observed on sweet potato in the field, and was not found in a survey of sweet potatoes prepared for export in Hawaii (Follett et al. 2007). Taro exports from Hawaii to the mainland USA require visual inspection and cutting of corms to identify infestations by a number of arthropod pests. No ginger weevils have been observed in over 30 years of this inspection regime in taro corms grown in the production area in east Hawaii (Follett et al. 2007).

4.2.1 Probability of entry Probability of importation

The likelihood that Elytroteinus subtruncatus will arrive in Australia with the importation of fresh taro corms from any country where this pest is present is: LOW. • The weevil larva burrows into the taro corm where it completes development. Feeding

gives rise to wilting, loss of vigour, and in severe infestations the plants die (Mau and Martin Kessing 1992a). Affected corms will show signs of rot and are likely to be detected and rejected during normal harvesting and grading operations.

• The main risk would be from corms in which eggs were laid late in the season, just before harvest, or after harvest during storage. This is possible, as Fiji ginger weevil is noted as a long-term storage pest in root crops such as yams (Dioscorea spp.) (Wilson 1987).

• Taro corms are known to host Elytroteinus subtruncatus, although no weevils have been detected in over 30 years of taro exports from east Hawaii where the weevil is present (Follett et al. 2007).


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• Weevil larvae and pupae have been found on sweet potato from Hawaii imported into mainland USA, but has not been confirmed as a pest of sweet potato under natural field conditions (Shea 2004; Follett et al. 2007).

• One weevil was intercepted in Sydney on unspecified goods from Fiji in 1963 (APPD 2009). Taro has been imported into Australia for many years from a number of Pacific countries where Elytroteinus subtruncatus is present without any further interceptions of the pest.

Probability of distribution

The likelihood that Elytroteinus subtruncatus will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country where this pest is present, is: MODERATE. • The weevil larva will remain within the corm for some time, as pupation occurs at the

feeding site inside the corm (Mau and Martin Kessing 1992a). Emergence of adult weevils may not occur until some time after arrival in Australia.

• Corms will be distributed to many localities by wholesale and retail trade and by individual consumers.

• Individual consumers could carry small quantities of taro corms to urban, rural and natural localities. Small amounts of corm waste could be discarded in these localities.

• Some corms will be distributed to areas where taro or other host species grow. • Small amounts of corm waste will be discarded into domestic compost. • Infested corms that escaped detection during processing and importation are likely to be

distributed in the wholesale and retail supply chain. • Elytroteinus spp. weevils are flightless (NZ MAF 2008) and have a limited ability to seek

out new hosts once they leave the corm.

Probability of entry (importation × distribution)

The likelihood that Elytroteinus subtruncatus will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country where this pest is present, is: LOW.

4.2.2 Probability of establishment The likelihood that Elytroteinus subtruncatus will establish within Australia, based on a comparison of factors in the source and destination areas considered pertinent to its survival and reproduction, is: LOW. • On lemons, Miller (1923) reported that only a single egg was laid in each fruit, so the fruit

only contained a single larva. It is not known if this behaviour also occurs on taro corms, but it is considered likely.

• For this pest to establish, it would need to complete its lifecycle. This could occur if several infested corms remained together in the supply chain, or if a single corm carried several eggs (oviposited by multiple females, as each female probably lays only a single egg in the corm), the pupae hatched, the adults survived and mated, and several females found suitable plants for their eggs. The combined probability of all these events happening is considered to be low.


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4.2.3 Probability of spread The likelihood that Elytroteinus subtruncatus will spread within Australia, based on a comparison of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of the pest, is: MODERATE. • Climatic conditions in parts of northern Australia are similar to conditions in the Pacific

countries where the weevil is found. • Host plants, including avocado, lemon, sugarcane and taro (Follett et al. 2007), are

available in many parts of Australia, so some spread could be anticipated. • Elytroteinus subtruncatus has not spread widely in Hawaii since it was first reported in

1918, despite the presence of hosts such as avocado and taro. Its distribution is restricted to parts of the island of Oahu (Follett et al. 2007).

• Elytroteinus spp. weevils are flightless (NZ MAF 2008), so natural spread would be slow. Longer distance spread would only occur via movement of infested plant material.

4.2.4 Probability of entry, establishment and spread The likelihood that Elytroteinus subtruncatus will be imported as a result of trade in fresh taro corms from any country where this pest is present, be distributed in a viable state to a susceptible host, establish and spread within Australia, is: VERY LOW.

4.2.5 Consequences Assessment of the potential consequences (direct and indirect) of Elytroteinus subtruncatus for Australia is: VERY LOW.

Criterion Estimate and rationale

Direct

Plant life or health

Impact score: C – minor significance at the district level This weevil has not been recorded as having a significant impact on taro. It has been noted as a major pest of soft-stemmed shrubs such as kava (Fakalata 1981) and begonia (Simmonds 1928), and a minor pest of other crops such as avocado, lemon and sugar cane (Follett et al. 2007). It can also be a storage pest of root crops such as yams (Wilson 1987).

Other aspects of the environment

Impact score: A – indiscernible at the local level There are no known direct consequences of this weevil on the natural or built environment.

Indirect

Eradication, control etc.

Impact score: B – minor significance at the local level Control measures in the field and packing house are confined to hygiene measures (removal of affected plants etc).

Domestic trade Impact score: B – minor significance at the local level A small effect on domestic trade in taro could be expected, with the need for quality controls and perhaps restrictions on movement of corms. Other crops such as lemons, and horticultural trade in Dracaena and Cordyline might be affected, although of only minor significance.

International trade

Impact score: B – minor significance at the local level The export trade of taro from Australia is small. Any impact is likely to be via other crops, where some restrictions might be imposed, particularly on commodities such as avocado and lemon where larvae feed inside the fruit. The mainland USA has restrictions on taro, ginger and sweet potato imports from Hawaii due to Elytroteinus subtruncatus (Follet et al. 2007).


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Environmental and non-commercial

Impact score: A – indiscernible at the local level No information was found indicating possible indirect effects on the environment.

4.2.6 Unrestricted risk estimate

The unrestricted risk for Elytroteinus subtruncatus is: NEGLIGIBLE.

Unrestricted risk is the result of combining the probability of entry, establishment and spread with the outcome of overall consequences. Probabilities and consequences are combined using the risk estimation matrix shown in Table 2.5.

The unrestricted risk estimate for the Elytroteinus subtruncatus of ‘negligible’ achieves Australia’s ALOP. Therefore, specific risk management measures are not required for this pest.

Review of import conditions for fresh taro corms Pest risk assessment – Taro beetles

25

4.3 Taro beetles Eucopidocaulus tridentipes; Papuana biroi; Papuana cheesmanae; Papuana huebneri; Papuana inermis; Papuana japenensis; Papuana laevipennis; Papuana semistriata; Papuana szentivanyi; Papuana trinodosa; Papuana uninodis At least 19 species of taro beetle are known, 18 in the genus Papuana and one in the genus Eucopidocaulus. The 11 species of taro beetles assessed in this PRA have been grouped together because of their similar biology. All pest species of Papuana and Eucopidocaulus tridentipes behave in a similar way, and they feed on the same hosts (TaroPest 2008). There are, however, minor differences in geographic and climatic ranges between the species, which do not affect the risk assessment.

The large (25 mm long and 12 mm wide) adult beetles burrow into the soft trunks, plant bases and corms of a range of plants, including taro, making large holes or cavities up to 2 cm in diameter (McGlashan 2006). Adult female beetles feed aggressively for about a week before leaving the host plant to seek suitable sites for egg laying (TaroPest 2008). These sites include felled logs, grassland with a silty loam topsoil, river beds and banks with good alluvial soil deposits, logging areas, gardens under fallow, and roadsides where there are host plants present (TaroPest 2008). The eggs are laid 5–15 cm beneath the soil (Onwueme 1999). The larvae hatch from the eggs in 11–16 days, and feed on plant roots and dead organic matter at the base of host plants (Onwueme 1999). The larvae rarely feed on taro corms (Macfarlane 1987). Adult males are most likely to be found in association with the corms, as they tunnel into the corms and remain there, whereas the females seek out sites for laying eggs after mating (SPC 2003).

Taro beetles are native to the Indo-Pacific region, with 18 species found in Papua New Guinea (Macfarlane 1987), 12–18 in the Solomon Islands, five in Vanuatu, and one each in Fiji, Kiribati and New Caledonia (Onwueme 1999; SPC 2003). About 11 or 12 species are serious pests of taro in the South Pacific region. There are a number of records of Papuana species being reported in Australia between 1909 and 1981 (APPD 2009). The records range from tropical to temperate regions. Five beetles identified only as Papuana sp. were recorded from the Iron Range in Queensland in 1968 (APPD 2009). A population of Papuana woodlarkiana is considered to be present in the far north of Queensland (Brooks 1965; Cassis et al. 1992). They have also been recorded at Onslow and Binningup in Western Australia (APPD 2009).

4.3.1 Probability of entry

Probability of importation

The likelihood that taro beetles will arrive in Australia with the importation of fresh taro corms from any country where these pests are present is: LOW. • Adult taro beetles are shiny and black, measuring approximately 25 mm long and 12 mm

wide. Newly emerged beetles are brown in colour (Carmichael et al. 2008). Adult beetles are likely to be detected if present in corms during harvest and grading operations.

• Adult beetles burrow into the underground part of taro corms, forming large holes and tunnels up to 2 cm in diameter (McGlashan 2006). The tunnels and associated frass are


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obvious. Affected corms are likely to be detected and discarded either at harvest or at the packing house.

• Affected corms are not suitable for human consumption. • The female beetles remain in the corms for only about a week and then spend most of

their time laying eggs in humic litter (SPC 2003). Beetles remaining in the corms are most likely to be males (SPC 2003).

• There is only one record of a taro beetle (an unidentified Papuana sp.) being found during Australian quarantine inspections of imported taro consignments in the available AQIS pest interception data since 1986.


The likelihood that taro beetles will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country where these pests are present, is: LOW. • It is possible that adult beetles could be transported in unopened cartons of taro. However,

only gravid females pose any risk, and these leave the corms after about a week to seek suitable substrates (humic soil) for oviposition. They are unlikely to remain associated with corms that have undergone harvest and pre-export sorting, grading and packing. Any beetles that remained in the corms after transport to Australia would be predominantly male.

• Should gravid females be imported, they are likely to leave the corms at the earliest opportunity and fly short distances seeking damp humic soil (leaf litter, compost, sawdust piles) to oviposit.


The likelihood that taro beetles will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country where these pests are present is: VERY LOW.

4.3.2 Probability of establishment The likelihood that taro beetles will establish within Australia, based on a comparison of factors in the source and destination areas considered pertinent to their survival and reproduction, is: MODERATE. • Native populations of taro exist in the Northern Territory. Extensive naturalised

populations of taro exist in Queensland, as well as in Western Australia and New South Wales. Taro is considered to be one of the 200 most invasive weeds in South East Queensland (Batianoff and Butler 2002).

• The climatic conditions in some parts of northern Australia are similar to the conditions in parts of the Pacific where taro beetles are found, such as Papua New Guinea.

• Taro beetles (Papuana spp.) have been recorded in Australia several times over the past century, but only Papuana woodlarkiana is considered to be present (Cassis et al. 1992; Brooks 1965). No other taro beetles have become established or spread, despite the presence of numerous hosts including Colocasia esculenta, a favourable climate, the use of various aroids as foliage plants in horticulture, and a taro industry that has existed in some form since the 1850s.

• Adult male beetles are the most likely stage to be present in the corms (SPC 2003) but would not establish a population.


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4.3.3 Probability of spread The likelihood that taro beetles will spread within Australia, based on a comparison of those factors in source and destination areas considered pertinent to the expansion of the geographic distribution of these pests, is: HIGH. • The experience in the Pacific shows that taro beetles will spread and become a serious

pest once established in tropical areas. Thus, if the beetles became established in a commercial taro growing area in Australia and remained uncontrolled, they could spread.

• Taro beetle larvae require a damp humic soil environment (e.g. the base of sugarcane clumps, banana plants, compost, sawdust piles or moist taro fields). Adult beetles require taro corms or similar soft trunks to complete their lifecycle. Both types of habitat are readily available in close proximity in northern Australia.

4.3.4 Probability of entry, establishment and spread The likelihood that taro beetles will be imported as a result of trade in fresh taro corms from any country where this pest is present, be distributed in a viable state to a susceptible host, establish and spread within Australia, is: VERY LOW.

4.3.5 Consequences Assessment of the potential consequences (direct and indirect) of taro beetles for Australia is: MODERATE.


Direct


Impact score: E – significant at the regional level Taro beetles are one of the three most serious taro pests (Onwueme 1999). In Papua New Guinea and Fiji, the beetles can cause yield losses of up to 30 percent (McGlashan 2006). Damage to the corms above 15 percent renders them unmarketable, even locally (Carmichael et al. 2008). The beetles may also attack other crops, such as sweet potatoes, yams and bananas (McGlashan 2006), palms (Masamdu and Simbiken 2000) and sugar cane (Carmichael et al. 2008). Australia has 44 species of native and naturalised aroids, 59 species of native and naturalised Ipomoea (sweet potatoes), five species of Dioscorea (yams) and 66 species of palms, all potentially susceptible to taro beetle attack. Three Typhonium species are listed as endangered: Typhonium jonesii, Typhonium mirabile and Typhonium taylori (EPBC 1999).


Impact score: A – indiscernible at the local level There are no known direct consequences of these beetles on the natural or built environment.

Indirect


Impact score: D – significant at the district level Should this pest establish in naturalised populations of Colocasia esculenta in South East Queensland and elsewhere, eradication would be very expensive. Even in crop situations, no single method of control is effective, and a combination of cultural, chemical, biological and phytosanitary control methods would be required (Carmichael et al. 2008).

Domestic trade Impact score: C – minor significance at the district level Grading can easily separate damaged and undamaged corms, allowing trade to continue with appropriate intra- and interstate controls. Only severely infested places of production would suffer major effects. Taro beetles may also affect crops such as sweet potatoes and yams. Domestic trade in other host commodities such as bananas, sugar and coffee would not be significantly affected, as the beetles mostly feed in the lower stems, plant bases and corms.


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International trade

Impact score: B – minor significance at the local level The taro export trade from Australia is small. Establishment of taro beetle in Australia is more likely to affect international trade in alternative hosts, such as sweet potatoes.




The unrestricted risk for taro beetles is: VERY LOW.


The unrestricted risk estimate for the taro beetles of ‘very low’ achieves Australia’s ALOP. Therefore, specific risk management measures are not required for these pests.

Review of import conditions for fresh taro corms Pest risk assessment – Taro planthopper

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4.4 Taro planthopper Tarophagus proserpina Taro planthoppers are pests of cultivated taro, directly damaging the plants through their feeding, as well as indirectly by vectoring viruses causing plant diseases such as alomae and bobone (Vargo 2000; Carmichael et al. 2008). The three recognised species of taro planthopper present in Asia and the Pacific are Tarophagus colocasiae, Tarophagus persephone and Tarophagus proserpina (Matthews 2003). Tarophagus colocasiae and Tarophagus persephone have been recorded in Australia (Matthews 2003).

The life history of Tarophagus proserpina occurs above ground, mostly on taro leaves (Matthews 2003). Eggs are laid in pairs in small holes made by the female in the petioles, petiole bases and the midribs of the leaves (Vargo 2000). There are five nymphal stages, lasting around 19 days depending on weather conditions (Vargo 2000). The young nymphs are creamy white, with black and white marking developing in the final stages (Matthews 2003; Carmichael et al. 2008). The adults are 3–4 mm in length, and black with broad white patches on the back of the thorax and abdomen (Carmichael et al. 2008). Like other Delphacidae planthoppers, for most of the year adult taro planthoppers have only short wings and cannot fly, but long-winged forms are often present during cooler periods, or when the taro host plants mature and die. The long-winged forms of Delphacidae can fly long distances. The rice brown planthopper, Nilaparvata lugens, has been reported flying more than 500 km (Matthews 2003).

Taro planthoppers predominantly feed on taro, although they have been observed on Alocasia spp. and Cyrtosperma spp. (Carmichael et al. 2008). The related Tarophagus persephone has also been collected on the weedy plants Mimosa pigra and Sida cordifolia in Australia, although these are not considered likely to be primary host plants (Matthews 2003). Adult and nymphal planthoppers usually congregate on the underside of the taro leaves, feeding on the sap. Reddish crusts form on the leaf surface where the sap oozes out (Vargo 2000). Heavy infestations can cause the leaves to wilt and turn yellow and, in exceptional cases, cause the plant to die (Carmichael et al. 2008).

Tarophagus proserpina is found from eastern Papua New Guinea across to Vanuatu, New Caledonia, the southern Pacific islands, French Polynesia and Hawaii (Matthews 2003). Two other species of taro planthoppers are already present in northern Australia. Tarophagus colocasiae is found in Far North Queensland and islands of the Torres Strait, while Tarophagus persephone has a wider distribution through northern Queensland and the Northern Territory (Matthews 2003). It has been suggested that the association of taro planthoppers with wild taro in Queensland pre-dates the more recent introductions on taro cultivars (Matthews 2003).


The likelihood that Tarophagus proserpina will arrive in Australia with the importation of fresh taro corms from any country where this pest is present is: HIGH. • Taro planthopper adults, nymphs and eggs are associated with the above ground parts of

the taro plant, including the petioles and petiole bases (Matthews 2003).


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• Untopped taro corms with the petiole bases and small tuft of petioles intact could harbour adults, nymphs and eggs.

• Taro planthoppers can survive long journeys as unhatched eggs or juvenile forms inside or on their host (Matthews 2003).

• The importation of taro planting materials was likely to be responsible for the introduction of Tarophagus proserpina into Polynesia (Matthews 2003).

• The female taro planthopper makes small holes in the leaf midrib, petioles or petiole bases into which two eggs are laid. The eggs would be difficult to detect. They hatch after 14 days (Vargo 2000), so it is possible that corms could arrive with eggs in the petioles. However, the outer petiole sheaths, which are most likely to have oviposition punctures, are typically removed during pre-export processing, thereby removing most eggs.

• Young nymphs are minute, almost clear and difficult to see (Carmichael et al. 2008) and could be present feeding amongst the petioles.

• Both adult and nymphal planthoppers are active and hop readily if they are disturbed (Vargo 2000). They feed on sap on the undersides of taro leaves, or on young unfurling leaves emerging from the petioles (Vargo 2000). The leaves are removed from the corm at harvest. Most adult and nymphal planthoppers will be disturbed during harvest and processing prior to export and hop from the corm, but some may remain amongst the petioles.

• Tarophagus proserpina is one of the most commonly intercepted pests on topped taro corms imported from Fiji (AQIS interception data).


The likelihood that Tarophagus proserpina will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country where this pest is present, is: HIGH. • The eggs of the planthopper hatch after 14 days (Vargo 2000), so any eggs laid in the

petioles or petiole bases in the days before the corms are harvested are likely to remain undetected and subsequently hatch some time after arrival in Australia.

• The movement of Tarophagus proserpina into Polynesia may be largely due to transport on planting materials, followed by establishment in taro gardens (Matthews 2003).

• Some adults and nymphs may remain concealed amongst the petioles. • Corms will be distributed to many localities by wholesale and retail trade and by

individual consumers. • Individual consumers could carry small quantities of taro corms to urban, rural and natural

localities. Small amounts of corm waste could be discarded in these localities. • Some corms will be distributed to areas where taro or other aroid species grow. • Small amounts of corm waste will be discarded into domestic compost. • Infested corms that escaped detection during processing and entry are likely to be

distributed in the wholesale and retail supply chain.


The likelihood that Tarophagus proserpina will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country where this pest is present, is: HIGH.


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4.4.2 Probability of establishment The likelihood that Tarophagus proserpina will establish within Australia, based on a comparison of factors in the source and destination areas considered pertinent to its survival and reproduction, is: HIGH. • Eggs laid in the petiole bases are a major source of infestation since propagation is by

means of corm tops with petiole bases (Matthews 2003). Imported corms with intact petiole bases could be diverted from consumption purposes to be used as planting material, significantly increasing the risk of establishment.

• Taro planthoppers are typically host-specific to taro, but are occasionally associated with other related plants such as Alocasia spp. and Cyrtosperma spp. (Carmichael et al. 2008). A number of species of these genera are common in many parts of Australia.

• Other taro planthopper species have established in wild taro populations in Queensland, typically around lowland swamps and watercourses. As the commercial cultivation of taro in Australia has been relatively limited up until recently, these planthopper populations in wild taro may pre-date the modern introduction of taro cultivars (Matthews 2003).

• The entire lifecycle takes place on the above ground parts of the taro plant. If the infestation is severe enough to kill the host plant, adults may seek out new hosts in which to oviposit.

• Cyrtorhinus fulvus, the mirid predator of taro planthoppers that regulates the pest population in much of the Pacific region (Fatuesi and Vargo 1995), is absent from Australia. Information on Australian mirid species that may potentially feed on Tarophagus proserpina is not available.

4.4.3 Probability of spread The likelihood that Tarophagus proserpina will spread within Australia, based on a comparison of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of this pest, is: MODERATE. • Climatic conditions in parts of northern Australia are similar to conditions in the Pacific

countries where the planthopper is found. • Tarophagus spp. have been associated with wild taro as well as cultivated taro (Matthews

2003). Host plants are widely available in many parts of Australia. Some spread could be anticipated if it became established.

• Adult planthoppers are capable of long distance migration under certain conditions, usually during cooler periods or when healthy host plants become scarce.

• Tarophagus spp. have extended beyond their natural range to the islands of Polynesia, Micronesia, Fiji, Vanuatu and Samoa where taro is an introduced crop (Matthews 2003).

• Two other species of taro planthopper are already present in northern Australia. These have not spread to southern Queensland or New South Wales, even though suitable hosts are widespread and common.

4.4.4 Probability of entry, establishment and spread The likelihood that Tarophagus proserpina will be imported as a result of trade in fresh taro corms from any country where this pest is present, be distributed in a viable state to a susceptible host, establish and spread within Australia, is: MODERATE.


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4.4.5 Consequences Assessment of the potential consequences (direct and indirect) of Tarophagus proserpina for Australia is: LOW.


Direct


Impact score: D – significant at the district level Taro planthoppers are important pests of taro, directly damaging plants through their feeding and indirectly through their transmission of viral plant diseases such as alomae and bobone (Vargo 2000; Carmichael et al. 2008). Taro planthoppers mostly feed on taro, but have also been reported on Alocasia spp. and Cyrtosperma spp. (Carmichael et al. 2008). Effects on other plant species are likely to be negligible.


Impact score: A – indiscernible at the local level There are no known direct consequences of taro planthoppers on the natural or built environment.

Indirect


Impact score: B – minor significance at the local level Other species of taro planthopper are already present in northern Australia. Existing control measures against these species would be effective against Tarophagus proserpina. The mirid egg predator Cyrtorhinus fulvus has successfully controlled Tarophagus spp. in many parts of the Pacific, although insecticides used against other pests may result in outbreaks of planthoppers by destroying the natural enemy populations (Fatuesi and Vargo 1995; Vargo 2000; Carmichael et al. 2008). However, Cyrtorhinus fulvus is not known to be present in Australia, and related Australian mirids such as Cyrtorhinus lividipennis have not been reported in association with taro (Cassis and Gross 1995).

Domestic trade Impact score: B – minor significance at the local level A small effect on domestic trade in taro could be expected, with the need for quality controls and perhaps restrictions on movement of corms. Other plant commodities are not affected by taro planthoppers.

International trade

Impact score: B – minor significance at the local level The export trade of taro from Australia is small. Taro planthoppers are already widespread through Asia and the Pacific. Other plant commodities are not affected by taro planthoppers.




The unrestricted risk of Tarophagus proserpina is: LOW.


The unrestricted risk estimate for Tarophagus proserpina of ‘low’ exceeds Australia’s ALOP. Therefore, specific risk management measures are required for this pest.

Review of import conditions for fresh taro corms Pest risk assessment – Mealybugs

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4.5 Paraputo mealybugs Paraputo aracearum; Paraputo leveri Paraputo is a genus of about 80–85 species of mealybugs of the New World, south Asia, China and the Pacific (Williams 2005; Ben-Dov et al. 2011). Only two species from the Pacific have been reported to be associated with taro. They are attended by ants, which milk them for honeydew, but very little is known of their lifecycles or epidemiology. Paraputo aracearum is known to feed exclusively on taro plants. Paraputo leveri is only a minor pest of taro, and is mostly associated with tree roots.

These two mealybugs have been grouped together in this pest risk assessment because of their similar biology (Williams 2005). Their lifecycle and behaviour are not well described, particularly for Paraputo aracearum, which so far has only been found in Fiji (Williams 2005). Paraputo leveri has a broader host range and geographical distribution.



The likelihood that Paraputo spp. will arrive in Australia with the importation of fresh taro corms from any country where these pests are present is: MODERATE. • Paraputo spp. of concern are distributed in South East Asia and the Pacific region. • Paraputo aracearum is only recorded from Fiji (Williams 2005). It has been intercepted

twice in California (in 1994 and 1996) on taro corms entering the USA from Fiji (Williams 2005).

• Paraputo leveri has been reported on taro in Papua New Guinea and Solomon Islands (Ecoport 2011). However, it is mainly found in association with tree roots, particularly coconut (Cocos nucifera) and coffee (Coffea spp.), on stems of bishopwood (Bischofia javanica), and on Tahitian chestnut (Inocarpus edulis), Balanophora sp. and Ficus sp. (Williams 2005).

• Paraputo leveri is often found on roots and may be carried on plant material (Williams 2005).

• Paraputo leveri has been intercepted on taro entering Hawaii from Western Samoa (Williams 2005).

• Mealybugs would mostly feed on the smaller roots, rather than the corm. These roots are removed from the corm before export.


The likelihood that Paraputo spp. will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country where these pests are present, is: MODERATE. • Mealybugs that escape detection at the border are likely to remain attached to the corms

and be distributed via the wholesale and retail supply chain. They are unlikely to be treated or destroyed in the retail supply chain unless the infestation is conspicuous.



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• Individual consumers will carry small quantities of taro corms to urban, rural and natural localities. Small amounts of corm waste could be discarded in these localities.

• Some corms could be distributed to areas where taro or other aroid species grow. • Small amounts of corm waste will be discarded into domestic compost. • Some corms of small corm taro may be planted for domestic cultivation instead of being

consumed.

Probability of entry (importation × distribution) The likelihood that Paraputo spp. will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country where these pests are present, is: LOW.

4.5.2 Probability of establishment The likelihood that Paraputo spp. will establish, based on a comparison of factors in the source and destination areas considered pertinent to their survival and reproduction, is: MODERATE. • Paraputo leveri has recently been found in a number of countries in the Pacific region,

and this has been interpreted as an indication that it may be invasive (Williams 2005). However, it may be that the mealybugs were native to those countries but previously overlooked. Paraputo aracearum is confined to Fiji and has shown no indication of being invasive (Williams 2005).

• Climatic conditions and host plants in parts of northern Australia would be comparable with those of the home range of these mealybugs.

• Paraputo leveri feeds on plants from at least ten families, including species that are relatively common in parts of Australia, such as mango (Mangifera indica), coffee (Coffea arabica) and grapevine (Vitis vinifera) (Ben-Dov et al. 2011).

4.5.3 Probability of spread

The likelihood that Paraputo spp. will spread within Australia, based on a comparison of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of the pest is: HIGH. • Local spread of Paraputo leveri is mediated by ants (Ben-Dov et al. 2011). Paraputo

leveri is associated with three ant species that are present in Australia: Pheidole megacephala, Oecophylla smaragdina and Odontomachus simillimus (Ben-Dov et al. 2011; AICN 2011). It is not known if Paraputo aracearum associates with ants, but it is possible since the behaviour is common in a number of other Paraputo spp. (Ben-Dov et al. 2011; McKey et al. 2005).

• Most Paraputo species in the Pacific are not noted for aggressive spread. Of the 44 Paraputo species, only two (Paraputo kukumi and Paraputo leveri) have been recorded throughout the Pacific region (Williams 2005).

• It appears that Paraputo leveri is extending its range and is considered to be invasive (Williams 2005).


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4.5.4 Probability of entry, establishment and spread

The likelihood that Paraputo spp. will be imported as a result of trade in fresh taro corms from any country where these pests are present, be distributed in a viable state to a suitable host, establish and spread within Australia is: LOW.

4.5.5 Consequences Assessment of the potential consequences (direct and indirect) of Paraputo spp. for Australia is: LOW.


Direct


Impact score: D – significant at the district level These mealy bugs have not been recorded as significant pests of taro. However, in Papua New Guinea Paraputo leveri is identified as a serious pest of coffee, damaging the roots and killing young trees (Ben-Dov et al. 2011). Australia has 44 species of native and naturalised aroids, and 66 species of palms (including coconut), all potentially susceptible to attack by Paraputo spp.. Three Typhonium species are listed as endangered: Typhonium jonesii, Typhonium mirabile and Typhonium taylori (EPBC 1999).


Impact score: A – indiscernible at the local level There are no known direct consequences of these mealybugs on the natural or built environment.

Indirect


Impact score: B – minor significance at the local level Programs to control these pests are unlikely to involve major expense. Paraputo species are moved about locally by ants (Ben-Dov et al. 2011), and control of the ants should control the spread of the mealybugs.

Domestic trade Impact score: B – minor significance at the local level Establishment of these pests on taro would be of concern in nearby coffee-growing areas or coconut plantations, and might necessitate some control measures. Some corms affected by mealybugs might not be saleable for aesthetic reasons, especially if the infestation was severe.

International trade

Impact score: B – minor significance at the local level Australia’s export trade in taro is small. Paraputo species are of quarantine concern in many countries (e.g. USA), and some extra costs might be incurred in cleaning produce destined for overseas markets. The impact, if any, is more likely to fall on other commodities. However, as these mealybugs feed on plant roots, contamination of fruit commodities such as mangoes, coconuts and grapes would not be expected.



4.5.6 Unrestricted risk estimate The unrestricted risk estimate for Paraputo spp. is: VERY LOW.


The unrestricted risk estimate for Paraputo spp. of ‘very low’ achieves Australia’s ALOP. Therefore, specific risk management measures are not required for these pests.

Review of import conditions for fresh taro corms Pest risk assessment – Yam scale

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4.6 Yam scale Aspidiella hartii Aspidiella is a genus of armoured (or hard) scales (Hemiptera: Diaspididae) of eight species, distributed in the tropical regions of the world (Ben-Dov et al. 2011). Aspidiella hartii has been reported in a number of Pacific Island countries where taro is grown, including Fiji, Papua New Guinea, the Solomon Islands, Tonga and Vanuatu (Ben-Dov et al. 2011; Wilson and Evenhuis 2007). Little is known of the lifecycle or biology of Aspidiella hartii (Watson 2011). Aspidiella hartii is mainly a pest of yam tubers and ginger rhizomes in storage, but taro is also a known host (Ben-Dov et al. 2011).

Members of the Diaspididae family are called armoured scales because they produce a hard, fibrous, wax-like covering (Carver et al. 1991) that attaches them to the host plant. Unlike the soft scales, armoured scales do not produce the honeydew-like secretions that commonly cause sooty mould to develop (Beardsley and Gonzalez 1975).

Feeding by armoured scales affects their hosts by removing sap, and injected saliva contains toxic enzymes that can damage the host plant (Beardsley and Gonzalez 1975). Leaf chlorosis and other localised effects are often associated with armoured scale infestations (Beardsley and Gonzalez 1975). High populations of scales can cause the death of branches or even entire trees (Beardsley and Gonzalez 1975; Watson 2011).

Scale nymphs typically settle and feed on the host plant, becoming immobile as they develop into late instar nymphs (Beardsley and Gonzalez 1975). The female reaches sexual maturity without undergoing true metamorphosis, remaining legless and immobile on the host plant. There is no pupal stage in the female lifecycle. The male scale has a pupal stage, subsequently emerging as a winged adult form. The female life stages are egg, nymph and adult, while the male has egg, nymph, pre-pupal, pupal and adult stages (Beardsley and Gonzalez 1975).

The scale covering the mature adult female Aspidiella hartii is circular, brown to brownish grey, and around 1–2.5 mm in diameter (Mau and Martin Kessing 1992b; Watson 2011). The scale cover of the mature male is smaller and more elongate than that of the female (Watson 2011). The adult males of most armoured scales are winged and capable of flight. They are tiny, fragile and lack functional mouthparts, so cannot feed. They are short-lived, generally living for only a few hours (Beardsley and Gonzalez 1975).

Reproduction in most armoured scales is sexual, although some reproduce by parthenogenesis, and some species have both sexual and parthenogenetic races (Beardsley and Gonzalez 1975; Watson 2011). Aspidiella hartii is thought to reproduce sexually (Watson 2011) like most other armoured scales (Beardsley and Gonzalez 1975). After fertilization, the female starts to lay eggs under her scale. Newly hatched crawlers usually remain sequestered for a period beneath the maternal scale, although it is typically only a few hours to a few days after hatching before they emerge (Beardsley and Gonzalez 1975).

Crawlers, which are the first nymphal instar, are the primary dispersal stage and move to new areas of the plant, or are dispersed by wind, or via contact with flying insects or birds (Watson 2011). The crawlers can move up to a metre under their own locomotion (Watson 2011). At the end of the wandering period (dispersal phase), crawlers secure themselves to the host plant with their mouthparts. Once settled, the larvae draw their legs beneath the body and flatten themselves against the host (Koteja 1990). They then insert their piercing and sucking


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mouthparts into the plant tissue and start feeding on plant juices (Beardsley and Gonzalez 1975; Koteja 1990).



The likelihood that Aspidiella hartii will arrive in Australia with the importation of fresh taro corms from any country where these pests are present is: VERY LOW. • Aspidiella hartii is present in a number of countries where taro is grown. This includes

many Pacific Island countries such as Fiji, Papua New Guinea, the Solomon Islands, Tonga and Vanuatu (Ben-Dov et al. 2011).

• Aspidiella hartii is mainly a pest of yams, ginger, sweet potato and tannia (Devasahayam and Abdulla Koya 2005), but is also known to attack taro (Williams and Watson 1988).

• Aspidiella hartii does affect crops in the field, but is particularly known as a storage pest of root and tuber crops (Williams and Watson 1988; Devasahayam and Abdullah Koya 2005).

• The storage life of taro corms for human consumption is considerably shorter than that of yams and ginger, so scale population numbers do not have time to build up to the same degree as on these other crops.

• Heavy infestations are likely to be noticed, as feeding causes desiccation of tissues, which become white, fibrous and unpalatable (Watson 2011). On ginger, the rhizomes are disfigured by the white underscales left behind where the scales were feeding (Watson 2011).

• Small numbers of scales on taro corms could escape detection during pre-export handling, as late instar nymphs and adult females are immobile. The circular scale covering is brown to brownish-grey in colour, and around 1–2.5 mm in diameter (Mau and Martin Kessing 1992b; Watson 2011). The scale is usually well hidden except in heavy infestations (Watson 2011).

• Aspidiella hartii is not represented in the available Australian quarantine interception data covering more than 20 years of taro imports. Unidentified Diaspididae scales have been found on imported taro on at least two occasions (1991 and 2003). While this species is known to be a storage pest, the conditions under which taro has been exported do not appear to favour this.


The likelihood that Aspidiella hartii will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country where these pests are present, is: MODERATE. • Scales that escape detection at the border are likely to remain attached to the corms and be

distributed via the wholesale and retail supply chain. These scales are unlikely to be treated or destroyed in the retail supply chain unless the infestation is conspicuous.

• Crawlers may emerge from under the scales of adult females and crawl short distances, or be blown by wind or carried by birds to new hosts.



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• Some corms could be distributed to areas where taro, ginger, yams or other host plants grow.

• Small amounts of corm waste will be discarded into domestic compost. • Some corms of small corm taro may be planted for domestic cultivation instead of being

consumed.

Probability of entry (importation × distribution) The likelihood that Aspidiella hartii will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country where these pests are present, is: VERY LOW.

4.6.2 Probability of establishment The likelihood that Aspidiella hartii will establish, based on a comparison of factors in the source and destination areas considered pertinent to their survival and reproduction, is: MODERATE. • The main risk for establishment is posed by the first instar larvae, as they are capable of

seeking out suitable hosts over short distances if introduced into the environment. • First instar larvae may be blown off the taro corms during transport. However, the

likelihood of these larvae landing on or near suitable hosts via wind dispersal would be low.

• Aspidiella hartii is thought to reproduce sexually (Watson 2011), like most other armoured scales (Beardsley and Gonzalez 1975).

• Adult males of sexually reproducing Diaspididae may have flight capability, but are unable to establish populations (Moran and Goolsby 2010).

• Males only live for a few hours, so have a limited period in which to find a mate. • An imported single gravid female may be all that is necessary to initiate an infestation

(Beardsley and Gonzalez 1975). However, establishment of a population would require both male and female crawlers to find hosts in close proximity and complete their development, and then for the flying adult male to locate an adult female for mating.

• Receptive adult female scales release pheromones to attract males. Information on flight ability of male Aspidiella hartii is not available, but the males of California red scale (Aonidiella aurantii) have been recovered up to 189 m downwind and 92 m upwind from release points. However, they were unable to fly upwind when the wind velocity exceeded 1.6 km per hour (Beardsley and Gonzalez 1975).

• Cold winter temperatures are likely to be a limiting factor in the potential establishment of Aspidiella hartii (Soltic and Peacock 2006). Climatic conditions, particularly temperature, humidity and rainfall, influence the rate of development and survival of armoured scale species (Beardsley and Gonzalez 1975).


The likelihood that Aspidiella hartii will spread within Australia, based on a comparison of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of the pest is: HIGH.


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• Once established, Aspidiella hartii is likely to spread wherever suitable host plants and favourable climate occur.

• Natural spread would occur slowly through the movement of crawlers blown by the wind or carried by flying insects or birds (Watson 2011), although specific information on dispersal of Aspidiella hartii is lacking.

• Dispersal of crawlers via wind or animals is not directional, reducing the likelihood of the crawlers locating a suitable host.

• First instar crawlers of Diaspididae have limited ability to move unassisted. In the absence of wind or other assisted dispersal, crawlers normally settle on the same host plants as the parents (Magsig-Castillo et al. 2010).

• The movement of infested tubers or rhizomes of tropical root crops, especially if they are used for planting purposes or stored with other root crops to be used for planting, is the most likely means of long distance dispersal for Aspidiella hartii (Watson 2011).

• Spread by movement of non-propagative plant material such as fruits, edible tubers, cut flowers etc would be unlikely, as establishment would require infested material to be placed in close proximity to a suitable host (Beardsley and Gonzalez 1975).

• The small size and sessile habits of these species mean that an infestation may not be discovered until it is too late to eradicate it (Beardsley and Gonzalez 1975).


The likelihood that Aspidiella hartii will be imported as a result of trade in fresh taro corms from any country where these pests are present, be distributed in a viable state to a suitable host, establish and spread within Australia is: VERY LOW.

4.6.5 Consequences Assessment of the potential consequences (direct and indirect) of Aspidiella hartii for Australia is: LOW.


Direct


Impact score: D – significant at the district level These scale insects feed on the phloem of hosts. Feeding damage from individual scales is minor, but large populations may develop, resulting in yellowing, defoliation, reduction in fruit set and loss of plant vigour (Mau and Martin Kessing 1992b). Symptoms may not appear on foliage or stems, although stunted growth may result from heavy infestations (Watson 2011).


Impact score: A – indiscernible at the local level There are no known direct consequences of this scale on the natural or built environment.

Indirect


Impact score: B – minor significance at the local level Programs to control this pest are unlikely to involve major expense. Control procedures for endemic scale species may be effective. Aspidiella hartii has been eradicated from Hawaii (Mau and Martin Kessing 1992b), although details of the eradication program are not available.

Domestic trade Impact score: B – minor significance at the local level Some yams and ginger may be destroyed in storage or may not be saleable if the infestation was severe.


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International trade

Impact score: B – minor significance at the local level Australia’s export trade in root crop hosts such as taro, ginger and yams is small. Aspidiella hartii is unlikely to have a significant impact on international trade.



4.6.6 Unrestricted risk estimate The unrestricted risk estimate for Aspidiella hartii is: NEGLIGIBLE.


The unrestricted risk estimate for Aspidiella hartii of ‘negligible’ achieves Australia’s ALOP. Therefore, specific risk management measures are not required for these pests.

Review of import conditions for fresh taro corms Pest risk assessment – Taro root aphid

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4.7 Taro root aphid Patchiella reaumuri Patchiella reaumuri has been reported on taro, although it may also feed on other species of Araceae. It congregates on the fibrous roots of taro and in very severe infestations moves to the leaf sheaths and petioles. Patchiella reaumuri does not produce winged sexual forms, and reproduction occurs by parthenogenesis, i.e. without fertilization (Sato and Hara 1997).

Patchiella reaumuri is only recorded from Europe, Hawaii and the Solomon Islands. In Europe, its hosts are a number of Arum and Tilia spp. (Macfarlane 1999; Carmichael et al. 2008). However, in the Pacific it is highly host specific. It is a serious pest of taro on the Hawaiian islands of Hawaii and Oahu, where crop losses of 75–100 percent are recorded for some varieties (Sato and Hara 1997).


The likelihood that Patchiella reaumuri will arrive in Australia with the importation of fresh taro corms from any country where this pest is present is: LOW. • Only taro corm imports from Hawaii and the Solomon Islands present a risk, as taro root

aphid is confined to these taro-growing locations. • Taro root aphid is also present in Europe, which does not produce or export taro. • Hawaii has official internal controls on the movement of taro from areas affected by taro

root aphid. Infested taro corms from Hawaii are unlikely to be exported. • Cleaning of taro corms during harvest, removal of the roots, grading and packing should

reduce the risks, and allow any aphids still present to be detected. • Removal or drying (during storage prior to export) of the fibrous roots, on which the

aphids feed, will reduce the risk of aphids being present.


The likelihood that Patchiella reaumuri will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country where this pest is present, is: LOW. • Taro root aphids in the Pacific are wingless (Macfarlane 1999; Sato and Hara 1997).

Aphids that escape detection at the border are likely to remain attached to corms and be distributed via the wholesale and retail supply chain. They are unlikely to be treated or destroyed in the retail supply chain unless the infestation is conspicuous.

• The aphids feed on the fine fibrous roots. The longer the taro corms remain in the retail chain, the more these fibrous roots will dry, and the fewer aphids will survive.


• Individual consumers could carry small quantities of taro corms to urban, rural and natural localities. Small numbers of corms could be discarded in these localities.

• Wholesalers and retailers will dispose of small numbers of damaged or unsold whole corms. This waste will be sent to municipal tips, where aphids are unlikely to survive


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because the waste is buried under other rubbish, and they will not be able to locate new hosts.

• Most corms will be consumed. Any taro not consumed will be discarded and sent to municipal tips or disposed of in garden compost. Some corms may be discarded into the environment, which may place aphids in proximity to wild or cultivated taro.

• Patchiella reaumuri has a very narrow host range. To be distributed, the wingless aphids need to travel from infested taro corms to a taro plant. This might be feasible in a backyard situation where an infested corm was discarded in proximity to a growing crop, but discarded corms are likely to be in poor condition or rotting and no longer have aphids feeding on them


The likelihood that Patchiella reaumuri will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country where this pest is present, is: VERY LOW.

4.7.2 Probability of establishment The likelihood that Patchiella reaumuri will establish within Australia, based on a comparison of factors in the source and destination areas considered pertinent to their survival and reproduction, is: MODERATE. • Patchiella reaumuri can reproduce without fertilization by males (Sato and Hara 1997),

which would increase the likelihood of establishing a population. • In Hawaii, short distance transport of these wingless aphids is mediated by ants

(Macfarlane 1999; Carmichael et al. 2008). There is no information on how specific this relationship is, but Australian ants are known to farm aphids for honeydew.

• Arum spp. act as alternative hosts for Patchiella reaumuri in Europe (Macfarlane 1999; Carmichael et al. 2008), so other species of Araceae (native, naturalised or cultivated) might act as alternative hosts for this aphid.

4.7.3 Probability of spread The likelihood that Patchiella reaumuri will spread within Australia, based on a comparison of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of the pest, is: MODERATE. • It is likely that ant vectors would be available to transport taro root aphids locally if they

established in areas with taro. • Most wild and naturalised taro in Australia is found in wet areas (along creeks etc.), which

are known to be unsuitable habitats for this aphid (Sato and Hara 1997). • Most Australian commercial taro is grown under dryland conditions, which are favourable

for taro root aphid. • Other possible host genera, Arum and Tilia, are not native or naturalised in Australia, and

occur only as sparsely distributed horticultural plants. It is not known if the Arum lily (Zantedeschia aethiopica), a weed introduced from South Africa that is common in parts of coastal southern Australia, would be an effective host for the taro root aphid.

• If the taro root aphid established in an Australian taro growing region, it could spread via movement of locally produced corms.


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4.7.4 Probability of entry, establishment and spread The overall likelihood that Patchiella reaumuri will enter Australia as a result of trade in fresh taro corms from any country where this pest is present, be distributed in a viable state to a susceptible host, establish and spread within Australia, is: VERY LOW.

4.7.5 Consequences Assessment of the potential consequences (direct and indirect) of Patchiella reaumuri for Australia is: MODERATE.


Direct


Impact score: E – significant at the regional level If this pest became established in dryland taro crops it could potentially be very serious, depending on the varieties of taro involved. In Hawaii, losses of 75–100 percent have been recorded from some varieties (Sato and Hara 1997). Australia has 44 species of native and naturalised aroids, all potentially susceptible to taro root aphid attack, although it is not known how many might be affected. If this pest was to establish in naturalised taro populations, this would be beneficial in a biocontrol sense for weedy taro but it would form a source for infestation back into taro crops.


Impact score: A – indiscernible at the local level There are no known direct consequences of this aphid on the natural or built environment.

Indirect


Impact score: C – minor significance at the district level Tillage and crop rotation are used to eradicate small scale infestations. No chemical controls are suitable, although controlling ants should reduce local spread. A hot water dip treatment for planting material has been found to be effective in Hawaii (Sato and Hara 1997).

Domestic trade Impact score: B – minor significance at the local level The pest is very host specific. The main consequences would arise from quarantine restrictions to prevent further spread to other taro growing areas.

International trade

Impact score: B – minor significance at the local level Australia's taro export trade is small. Taro root aphid would be considered a quarantine pest for most countries.




The unrestricted risk for Patchiella reaumuri is: VERY LOW.


The unrestricted risk estimate for Patchiella reaumuri of ‘very low’ achieves Australia’s ALOP. Therefore, specific risk management measures are not required for this pest.

Review of import conditions for fresh taro corms Pest risk assessment – Spiral nematodes

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4.8 Spiral nematodes Helicotylenchus microcephalus; Helicotylenchus mucronatus Helicotylenchus species are polyphagous plant parasitic root feeders that are found throughout tropical and subtropical regions of the world. Helicotylenchus is the most common plant nematode genus in Fiji (Orton Williams 1980). A number of spiral nematode species are present in Australia, including Helicotylenchus multicinctus, which is a serious pest of banana and sugarcane (McLeod et al. 1994).

Helicotylenchus microcephalus and Helicotylenchus mucronatus are pest species that feed on taro. Neither species has been reported in Australia. These two species have been grouped together for this PRA due to their similar biology.

The lifecycles and biology of these species are not well documented. Helicotylenchus spp. nematodes are usually ectoparasitic feeders on roots, but they can sometimes feed inside the roots (Kazi 1996; Luc et al. 1990). All life stages can be found in the soil and root cortex. Migration through the root tissues has not been reported. Small lesions are formed that become necrotic as secondary infections take place. The two species considered here are parthenogenetic (Luc et al. 1990). There are other Helicotylenchus species known to occasionally feed on taro that have not been reported as causing economic damage. The similar biological characteristics of these species means they would pose similar risks in terms of entry, distribution, establishment and spread.


The likelihood that Helicotylenchus microcephalus and Helicotylenchus mucronatus will arrive in Australia with the importation of fresh taro corms from any country where these pests are present is: LOW. • Helicotylenchus microcephalus and Helicotylenchus mucronatus are polyphagous (Luc et

al. 1990), and are associated with the roots of many different hosts, including taro. • Helicotylenchus microcephalus and Helicotylenchus mucronatus have been identified as

minor pests of taro (Bridge 1988; Orton Williams 1980). • While the lifecycle and biology of both species is not well documented, they are likely to

predominantly feed on the outside of the roots like other Helicotylenchus species (Kazi 1996). However, Helicotylenchus microcephalus is reported to be endoparasitic in sweet potato roots by Njuguna and Bridge (1998).

• All life stages can be found in the root cortex of host plants, but migration through (i.e. inside) the root tissues has not been reported (Luc et al. 1990). Their association is with the roots, rather than the corm.

• The most likely pathway for entry would be via infested soil attached to poorly cleaned corms.

• Removal of feeder roots as part of the cleaning process, and drying of any remaining roots and the surface of the corm in storage will further reduce the numbers of nematodes.


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The likelihood that Helicotylenchus microcephalus and Helicotylenchus mucronatus will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country where these pests are present, is: MODERATE. • These nematodes are not known to penetrate deeply into root tissue, and they remain on or

near the surface (Luc et al. 1990). As the outer surfaces of the corm and the fine feeder roots dry during storage and distribution, conditions will become less favourable for survival of the nematodes.


• Individual consumers could carry small quantities of taro corms to urban, rural and natural localities. Small amounts of corm waste could be discarded in these localities.

• Some corms will be distributed to areas where host plants are grown. • Small amounts of corm waste will be discarded into domestic compost. • Living nematodes in discarded taro waste may be able to find a compatible host in the

area where they are discarded. Spiral nematodes are polyphagous, feeding on a wide range of plant hosts (Luc et al. 1990).

• Their ability to move from the corm to locate a new host is very limited. • Active movement of nematodes in the soil is probably limited to several centimetres per

year. Movement is dependent on moisture, and will be affected by rainfall, soil texture, compaction and structure, and slope position (Norton and Niblack 1991). Longer distance movement may occur via surface water or wind currents (Norton and Niblack 1991).


The likelihood that Helicotylenchus microcephalus and Helicotylenchus mucronatus will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country where this pest is present, is: LOW.

4.8.2 Probability of establishment The likelihood that Helicotylenchus microcephalus and Helicotylenchus mucronatus will establish within Australia, based on a comparison of factors in the source and destination areas considered pertinent to their survival and reproduction, is: HIGH. • Climatic conditions in parts of Australia will match those in source areas. • These nematodes feed on the roots of a broad range of plants. Helicotylenchus

microcephalus has been recorded on more than 60 different plant hosts, most commonly on breadfruit, cassava, maize, peanut and sugarcane (Orton Williams 1980). Kazi (1996) reported 23 plant hosts of Helicotylenchus mucronatus, many of which are present and common in Australia, such as capsicum, citrus, corn, cucumber, mango, potato, rice and sugarcane.

• Nematodes in the vicinity of roots of host plants will be able to feed and reproduce.

4.8.3 Probability of spread The likelihood that Helicotylenchus microcephalus and Helicotylenchus mucronatus will spread within Australia, based on a comparison of those factors in the source and destination


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areas considered pertinent to the expansion of the geographic distribution of the pests, is: HIGH. • Spread of these nematodes is thought to occur mainly by the planting of infested material

and movement of soil. • If the nematodes established in growing areas, it is possible that they could remain

undetected for some time, causing little damage, and may then be inadvertently spread via planting stock.

• Spread is also possible by transfer to alternative hosts and subsequent propagation via that pathway.

• Natural spread would be slow, as nematodes only actively move several centimetres per year in the soil (Norton and Niblack 1991). However, nematodes on the soil surface could be carried greater distances by wind or surface water.

4.8.4 Probability of entry, establishment and spread The overall likelihood that Helicotylenchus microcephalus and Helicotylenchus mucronatus will be imported as a result of trade in fresh taro corms from any country where these pests are present, be distributed in a viable state to a susceptible host, establish and spread within Australia, is: LOW.

4.8.5 Consequences Assessment of the consequences (direct and indirect) of Helicotylenchus microcephalus and Helicotylenchus mucronatus for Australia is: LOW.


Direct


Impact score: D – significant at the district level There is no evidence that spiral nematodes seriously affect taro, although Helicotylenchus mucronatus has been identified as a potential problem (Bridge 1988). Their main impact would probably be on other crops such as sugarcane and bananas, which are already subject to infestation by more aggressive Helicotylenchus spp.. They may also infest aroid foliage plants that are part of the horticultural trade. Existing control measures for those other species would mitigate the effect of these spiral nematodes.


Impact score: A – indiscernible at the local level There are no known direct consequences of these nematodes on the natural or built environment.

Indirect


Impact score: C – minor significance at the district level Once established, eradication of these species would not be possible. Control measures would be aimed at ensuring nematode-free planting stock. Treatment of planting material by immersion in hot water at 50 °C for 15–40 minutes has been shown to be effective in eliminating other nematode species from taro planting material without damaging the planting stock (Luc et al. 1990), although there is no published evidence that it would be equally effective for Helicotylenchus microcephalus and Helicotylenchus mucronatus. Impacts on other crops are possible because spiral nematodes are not host-specific. However, the crops most at risk (bananas, sugarcane) are already subject to attack by Helicotylenchus multicinctus, a more serious pest, and efforts to control that nematode would simultaneously control these species.

Domestic trade Impact score: B – minor significance at the local level Establishment of spiral nematodes in taro growing areas would possibly elicit controls on movement of produce to prevent further spread.


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International trade

Impact score: B – minor significance at the local level The export trade in taro from Australia is small. As infestations are confined to feeder roots, effects on trade in non-root crops are likely to be negligible. Both species are already widespread in countries likely to be recipients of exported taro.


Impact score: A – indiscernible at the local level Most recorded hosts are crop plants. Little information is available on the susceptibility of native plants to spiral nematodes. Pandanus sp. and Macadamia sp. are reported as hosts of Helicotylenchus microcephalus (Orton Williams 1980). No indirect environmental consequences of these nematodes are known.


The unrestricted risk for Helicotylenchus microcephalus and Helicotylenchus mucronatus is: VERY LOW.


The unrestricted risk estimate for Helicotylenchus microcephalus and Helicotylenchus mucronatus of ‘very low’ achieves Australia’s ALOP. Therefore, specific risk management measures are not required for these pests.

Review of import conditions for fresh taro corms Pest risk assessment – Taro root nematode

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4.9 Taro root nematode Hirschmanniella miticausa Hirschmanniella miticausa is a migratory endoparasitic nematode and the causal organism of the corm rot disease known as ‘miti miti’ in the Solomon Islands (Bridge 1988). The disease was first noted on the island of Choiseul, Solomon Islands, in the 1920s, but spread with the movement of planting material (Mortimer et al. 1981). The highest populations of the nematode live inside the taro corms, and some may be found in the roots. Only a few nematodes may be found in the surrounding soil (Bridge et al. 1983; Jatala and Bridge 1990).

Hirschmanniella miticausa is a serious pest of wetland cultivated taro, and is also considered to be a problem in dryland taro (Zettler et al. 1989). No other hosts are known. Although symptoms are usually only apparent when corms are harvested (Zettler et al. 1989), wilting, stunting and the eventual chlorosis of older leaves due to corm damage are the first above-ground symptoms of Hirschmanniella miticausa infestation (Carmichael et al. 2008). Infested corms exhibit irregular, small (1–10 mm wide) red or brown necrotic zones originating from the base of the corm (Bridge 1988; Carmichael et al. 2008). Infested corms have the appearance of uncooked fatty meat (hence the pidgin name ‘miti miti’ in the Solomon Islands) and often the basal parts of the corms succumb to secondary brown rots, resulting in their complete decay (Zettler et al. 1989; Carmichael et al. 2008).

Hirschmanniella miticausa has been reported from the Solomon Islands, and also has a limited distribution in the highlands of Papua New Guinea (Jatala and Bridge 1990; Bridge et al. 1983). Only taro imports from these countries pose a risk to Australia. An unspecified Hirschmanniella sp. has also been recorded as associated with taro in Taiwan (Jatala and Bridge 1990).



The likelihood that Hirschmanniella miticausa will arrive in Australia with the importation of fresh taro corms from any country where this pest is present is: MODERATE. • Plants infested with this nematode show signs such as wilting of leaves, yellowing and

distortion of the central leaf, and have reduced numbers of daughter corms. Affected plants usually die prematurely. The basal portions of the corms are often affected with a brown soft rot, as well as the dry brown rot of miti miti (Jatala and Bridge 1990). Such corms are unlikely to enter the export stream, and if they do, are likely to be detected during sorting, grading and packing.

• However, corms with only dry internal rot may escape detection, as symptoms may only be apparent when the corms are cut open (Carmichael et al. 2008).


The likelihood that Hirschmanniella miticausa will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country where this pest is present, is: LOW.


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• Corms with miti miti infestation are prone to secondary rots (Jatala and Bridge 1990), and it is likely that rotting would progress further during storage and transport within Australia, making the diseased corms more conspicuous and subject to culling.

• However, because some infested corms do not initially show obvious external symptoms, it is possible that a small number of these corms could be distributed in the wholesale and retail supply chain.



• Some corms will be distributed to areas where taro is grown. • Small amounts of corm waste could be discarded into domestic compost. • The most likely scenario for distribution would involve an infested corm entering the

retail supply chain undetected, being cut open and found to be rotten by a consumer, and then being discarded as waste (e.g. composted) near cultivated taro plants, for example, in a domestic garden.

• The nematode’s ability to move from the corm to locate a taro plant is very limited and dependant on factors such as soil moisture.


The likelihood that Hirschmanniella miticausa will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country where this pest is present, is: LOW.

4.9.2 Probability of establishment The likelihood that Hirschmanniella miticausa will establish within Australia, based on a comparison of factors in the source and destination areas considered pertinent to its survival and reproduction, is: HIGH. • Climatic conditions in northern Australia are similar to the native environment where taro

root nematode is found. • The nematode can probably survive for some time in field soil without hosts (Jatala and

Bridge 1990). • Nematodes in the vicinity of taro roots will be able to feed and reproduce. • Taro is the only known host of Hirschmanniella miticausa (Zettler et al. 1989). If the

local taro population was infested, it would provide a reservoir of infestation that would be difficult to eliminate.

• Despite other aroids growing in the area where the taro root nematode occurs, the nematode is not known to attack them, so it is unlikely that it will affect other native and naturalised aroids.

4.9.3 Probability of spread The likelihood that Hirschmanniella miticausa will spread within Australia, based on a comparison of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of the pest, is: MODERATE.


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• Hirschmanniella miticausa is migratory in soil and can spread short distances without relying on vectors. It can be carried in run-off water, particularly where taro is grown on hillsides (Jatala and Bridge 1990).

• Discarding infected material near watercourses would greatly increase the possibility of spread. Naturalised taro is commonly established alongside watercourses.

• Long distance spread of this pest is mainly via planting of infected propagating materials (Jatala and Bridge 1990) including headsetts, corm pieces or daughter corms. It is unlikely that infected plants would be used as propagating material in domestic situations, as infected material would show obvious symptoms.

4.9.4 Probability of entry, establishment and spread The likelihood that Hirschmanniella miticausa will be imported as a result of trade in fresh taro corms from any country where this pest is present, be distributed in a viable state to a susceptible host, establish and spread within Australia, is: LOW.

4.9.5 Consequences Assessment of the potential consequences (direct and indirect) of Hirschmanniella miticausa for Australia is: LOW.


Direct


Impact score: D – significant at the district level Hirschmanniella miticausa is a serious pest of taro grown in both wetland and dryland farming systems. In the Solomon Islands, where taro is grown in continuous cultivation in swamp pits, nematode infestation has led to local abandonment of taro growing (Jatala and Bridge 1990). However, Australian taro is usually grown as a dryland crop. Dryland conditions are less favourable for spread of Hirschmanniella miticausa, but do not eliminate its impact.


Impact score: A – indiscernible at the local level There are no known direct consequences of this nematode on the natural or built environment.

Indirect


Impact score: D – significant at the district level In subsistence situations, crop rotation and hygiene (selection of uninfested planting stock) is the main control measure. Planting material can be cleared of infestation by immersion in hot water at 50 °C for 15 minutes. Because the nematode is rarely found in the uppermost part of the corm, planting only headsets that have been carefully checked for infestation, and not using daughter corms and pieces of corm, can result in nematode-free crops. A resistant cultivar is known in the Solomon Islands, but it has poor eating qualities (Jatala and Bridge 1990).

Domestic trade Impact score: B – minor significance at the local level Establishment of this pest in taro growing areas may elicit controls on movement of produce to prevent further spread. No impact on other crops would be expected because the nematode is very host-specific.

International trade

Impact score: B – minor significance at the local level The export trade in taro from Australia is small, and the taro root nematode is not known to attack other crops.




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The unrestricted risk for Hirschmanniella miticausa is: VERY LOW.


The unrestricted risk estimate for taro root nematode of ‘very low’ achieves Australia's ALOP. Therefore, specific risk management measures are not required for this pest.

Review of import conditions for fresh taro corms Pest risk assessment – Needle nematode

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4.10 Needle nematode Longidorus sylphus The needle nematode Longidorus sylphus, a member of the Longidorus elongatus complex, has been reported to be associated with taro in Hawaii. Longidorus species are ectoparasites, attacking feeder roots just behind the growing tips, and have long stylets that can penetrate to the vascular tissue. Some of them have been implicated in virus transmission. The reported host range is diverse, consisting mostly of woody fruit trees, but also includes more herbaceous taxa such as sugarcane, mint and grapevines. Information on biology, and therefore on risk, is difficult to assess because of continuing disagreements on the taxonomic limits of species in the complex.


The likelihood that Longidorus sylphus will arrive in Australia with the importation of fresh taro corms from any country where this pest is present is: VERY LOW. • The association of this nematode with taro is based on a single record from Hawaii (Ooka

1994). Apart from Ooka (1994), none of the literature dealing with taro or taro pests and diseases mentions this pest in association with a disease of taro. No records of this pest in association with taro have been found for any other country.

• Needle nematodes are migratory ectoparasites. Their long stylets enable them to feed on deep tissues while remaining on the surface of the root, and they may even penetrate the stele (Merrifield 1999). Only feeder roots are likely to be affected.

• The Longidorus elongatus complex (i.e. including Longidorus sylphus) has not been recorded infecting tubers, corms or rhizomes in trade (CABI 2011). Most feeder roots are removed from taro corms in the standard cleaning process, and those remaining will desiccate and die.

• A major means of transport and dispersal is via infested soil. Removing soil from corms during harvest and grading operations will greatly reduce the risk.

• Only plant material from Iraq, Sudan, Belarus, Bulgaria, Moldova, Canada, mainland USA and Hawaii, where this pest has been reported to occur, poses any risk. Few of these countries are exporters of taro.


The likelihood that Longidorus sylphus will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country where this pest is present, is: LOW. • Longidorus sylphus is an ectoparasite that attacks the tips of feeder roots. Feeder roots are

removed from the corm during post-harvest processing. Any roots not removed are likely to dry out, limiting the viability of the nematode.

• Longidorus sylphus has a restricted host range. Most recorded hosts are fruit trees, but it has been suggested that records of association with these plants reflect only the presence of grasses in orchards (CABI 2011). However, potential host records are confused by taxonomic uncertainty surrounding Longidorus sylphus/Longidorus elongatus. Suitable hosts may be available in Australia.


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• Consumers will carry small quantities of taro corms to urban, rural and natural localities. Small amounts of corm waste could be discarded in these localities.

• Some corms will be distributed to areas where taro and other host plants grow. • Small amounts of corm waste could be discarded in domestic compost. • The nematode’s ability to move from the corm to locate a new host is very limited and

dependant on factors such as soil moisture.


The likelihood that Longidorus sylphus will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country where this pest is present, is: VERY LOW.

4.10.2 Probability of establishment The likelihood that Longidorus sylphus will establish within Australia, based on a comparison of factors in the source and destination areas considered pertinent to their survival and reproduction, is: MODERATE. • Longidorus species prefer cooler climates (Luc et al. 1990), so that, even if introduced on

taro, the nematode may find it difficult to establish in commercial taro growing areas, which tend to be in warmer climates. However, a number of other hosts including ornamental taro plants are found in cooler parts of Australia, so establishment is feasible.

• Nematodes in the vicinity of roots of host plants will be able to feed and reproduce. • Longidorus sylphus has been reported from grape vineyards (Ferris 1999). The

Longidorus elongatus complex is associated with many grasses and vegetable crops (CABI 2011), but the susceptibility of these plants specifically to Longidorus sylphus is largely unknown.

4.10.3 Probability of spread The likelihood that Longidorus sylphus will spread within Australia, based on a comparison of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of the pest, is: MODERATE. • The main mechanism for spread is transport of infested soil on produce or implements, or

live feeder roots of planting material. It could be spread on agricultural machinery that has not been cleaned.

• Longidorus sylphus is found principally on feeder roots of grasses, but it attacks a wide range of vegetable crops, and some tree crops (CABI 2011). Planting of some of these crops (e.g. sugarcane, taro) as rooted material from infected areas could spread the pest.

• The only record of Longidorus elongatus in Australia was on Lolium in South Australia (McLeod et al. 1994), which does not appear to have spread, as no further records are known.

• There are few records of Longidorus spp. in Australia. Longidorus taniwha has been recorded in South Australia, while unidentified Longidorus species have been recorded in New South Wales and Queensland (McLeod et al. 1994; APPD 2009). The paucity of records suggests that this genus is not widespread in (and perhaps not well-adapted to)


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Australia. In part, this may be because Longidorus species prefer cooler soils with adequate moisture to facilitate movement of the relatively long nematodes (CABI 2011).

4.10.4 Probability of entry, establishment and spread The likelihood that Longidorus sylphus will enter Australia as a result of trade in fresh taro corms from any country where this pest is present, be distributed in a viable state to a susceptible host, establish and spread within Australia, is: VERY LOW.

4.10.5 Consequences Assessment of the potential consequences (direct and indirect) of Longidorus sylphus for Australia is: LOW.


Direct


Impact score: D – significant at the district level There is no evidence that this nematode seriously affects taro. Its main economic impact, if introduced, established and spread, would be on other crops such as mint, grapevines and sugarcane. The main physical damage is swelling and galling of infested root tips and stunting of the root system. The main impact of nematodes of the Longidorus elongatus complex lies in their ability to transmit viruses, such as raspberry ring spot virus, tomato black ring virus and spoon leaf virus (CABI 2011).


Impact score: A – indiscernible at the local level There are no known direct consequences of this nematode on the natural or built environment.

Indirect


Impact score: C – minor significance at the district level Control measures for nematodes of the Longidorus elongatus complex are not well developed. For high value crops such as strawberry and raspberry susceptible to viral infection, the use of nematicides may have an economic benefit (Jensen and Horner 1957; Whitehead 1998; CABI 2011). Browning et al. (2004) found that butyric acid (formed by fermentation of organic material by anaerobic soil bacteria) was an effective nematicide for Longidorus sylphus.

Domestic trade Impact score: B – minor significance at the local level Establishment of this pest in taro growing areas would possibly elicit controls on movement of produce to prevent further spread.

International trade

Impact score: B – minor significance at the local level The export trade in taro from Australia is small. As the nematode is confined to feeder roots, effects on exports of non-root crops are likely to be negligible.


Impact score: A – indiscernible at the local level There is no evidence to suggest that this group of nematodes would affect native species, and records of the genus from Australia are sparse. No indirect environmental consequences of these nematodes are known.


The unrestricted risk for Longidorus sylphus is: NEGLIGIBLE.



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The unrestricted risk estimate for the needle nematode of ‘negligible’ achieves Australia’s ALOP. Therefore, specific risk management measures are not required for this pest.

Review of import conditions for fresh taro corms Pest risk assessment – Bacterial blight of taro

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4.11 Bacterial blight of taro Xanthomonas axonopodis pv. dieffenbachiae Bacterial blight has been reported on taro in India (Rachid et al. 1998; Phookan et al. 1996), Hawaii (Chase et al. 1992) and Papua New Guinea (Tomlinson 1987). Lipp et al. (1992) identified Xanthomonas campestris pv. dieffenbachiae as the pathogen responsible for blight in a number of aroid genera, including Aglaonema, Alocasia, Anthurium, Colocasia, Dieffenbachia, Epipremnum and Xanthosoma.

The disease is characterised by water-soaked interveinal lesions on the leaf margins that extend with time towards the centre and eventually cover the whole leaf lamina (Phookan et al. 1996). In the later stages, the lesions become dark brown. Bacterial exudates are observed on the undersides of leaves. In severe infections, the leaves dry and fall off (Phookan et al. 1996).

Xanthomonas dieffenbachiae was the name given to the bacterial pathogen responsible for bacterial blight of Dieffenbachia species by Dowson (1943). It was subsequently reported as causing disease on other aroids including Aglaonema, Anthurium and Philodendron. Young et al. (1978) reduced the species Xanthomonas dieffenbachiae to a pathovar of Xanthomonas campestris. A distinct pathovar, Xanthomonas campestris pv. aracearum, was identified by Berniac (1974) as causing leaf spot of malanga (Xanthosoma caracu), and recognised by Dye et al. (1980) for all xanthomonads causing leaf spots of aroids. However, this was later found to be a strain of Xanthomonas campestris pv. dieffenbachiae (Pohronezny and Dankers 1986). Vauterin et al. (1995) reclassified Xanthomonas campestris pv. dieffenbachiae as Xanthomonas axonopodis pv. dieffenbachiae.

Strains of Xanthomonas axonopodis pv. dieffenbachiae are genotypically and phenotypically diverse (Chase et al. 1992; Berthier et al. 1993; Robène-Soustrade et al. 2006; EPPO 2011a). At least eight strains are known to affect taro (Chase et al. 1992). These are less virulent and more host-specific than those affecting Anthurium, and result in a leaf blight disease that can cause extensive damage.

Rachid et al. (1998) planted seed corms sourced from taro plants infected by a pathogen identified only as Xanthomonas campestris, which subsequently produced new infected plants. The other literature on Xanthomonas infection of Araceae has not assessed systemic infection of Colocasia species or transmission of the bacterium via corms.



The likelihood that Xanthomonas axonopodis pv. dieffenbachiae will arrive in Australia with the importation of fresh taro corms from any country where this pathogen is present is: MODERATE. • Infection reduces the number of leaves, affecting corm size. Badly infected plants will not

produce commercially acceptable corms. • The bacteria are present in the leaves and in decaying dead leaf material in the

surrounding soil (Rachid et al. 1998). • The strain (or group of strains) affecting Colocasia species is less severe than the strains

affecting Anthurium, and mostly infects the leaves.


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• Leaves are removed and soil is cleaned from corms before export, reducing the risks presented by those sources.

• A highly pathogenic strain identified by Rachid et al. (1998) in India was reported to spread via seed corms. This is the only known report of a Xanthomonas infection associated with taro corms.

• Latent infections occur (Laguna et al. 1983; EPPO 2011a), as do systemic infections in other aroids (Chase et al. 1992; EPPO 2004), suggesting symptomless corms carrying the bacteria may be present and might be imported.


The likelihood that Xanthomonas axonopodis pv. dieffenbachiae will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country where this pathogen is present, is: MODERATE. • It is unclear whether the bacterium is present in the corm tissue, or only in the leaves and

petioles (Chase et al. 1992; EPPO 2004). If the disease is borne internally as a systemic infection of the corm, it will remain in the corm tissue through the distribution, sale and disposal of fresh taro corms.



• Some corms will be distributed to areas where taro or other aroid species grow. • Small amounts of corm waste could be discarded in domestic compost. • The bacterium could be distributed from corm waste to the leaves and petioles of hosts by

rain or water splash. • Some corms of small corm taro may be planted for domestic cultivation instead of being

consumed. These corms sprout much more readily than large corm taro (Colocasia esculenta var. esculenta), and therefore pose a higher risk of distributing the pathogen if it is present in the corms.


The likelihood that Xanthomonas axonopodis pv. dieffenbachiae will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country where this pathogen is present, is: LOW.

4.11.2 Probability of establishment

The likelihood that Xanthomonas axonopodis pv. dieffenbachiae will establish within Australia, based on a comparison of factors in the source and destination areas considered pertinent to its survival and reproduction, is: MODERATE.

• Susceptible genera include Colocasia, Aglaonema, Anthurium, Dieffenbachia, Epipremnum, Philodendron, Syngonium and Xanthosoma. These host plants are all present in Australia, and most are widely distributed. Many of these plants are grown for use as indoor plants.


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• Chase et al. (1992) demonstrated that while some degree of host specificity occurs with strains of Xanthomonas campestris, some strains from each host are able to infect and cause symptoms in plants from other genera.


The likelihood that Xanthomonas axonopodis pv. dieffenbachiae will spread within Australia, based on a comparison of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of the pest, is: HIGH. • Long distance dispersal of Xanthomonas axonopodis pv. dieffenbachiae is most likely to

occur by the transport and planting of infected taro corms and planting material of other hosts.

• Unintentional movement of infested soil is possible. • Xanthomonas axonopodis pv. dieffenbachiae spreads via latently infected plants, plant to

plant contact, water splash (rain and irrigation), wet clothing, insects, infested soil, contaminated tools and possibly nematodes (Laguna et al. 1983; EPPO 2011a).

• Areas where taro is grown, mainly in coastal parts of Queensland and northern New South Wales and around Darwin in the Northern Territory (Lemin 2006), would be suitable for the natural spread of this bacterium.

4.11.4 Probability of entry, establishment and of spread The likelihood that Xanthomonas axonopodis pv. dieffenbachiae will be imported as a result of trade in fresh taro corms from any country where this pathogen is present, be distributed in a viable state to susceptible hosts, establish and spread within Australia, is: LOW.

4.11.5 Consequences Assessment of the potential consequences (direct and indirect) of Xanthomonas axonopodis pv. dieffenbachiae for Australia is: LOW.


Direct


Impact score: D – significant at the district level Xanthomonas campestris has been reported as causing high levels of disease in Hawaii (Chase et al. 1992), and extensive damage to taro crops in Assam, India (Phookan et al. 1996). Disease caused by Xanthomonas pathovars causes large losses in Anthurium and Syngonium crops (Chase et al. 1992; EPPO 2004). It is unclear which other hosts would be affected by the strains associated with taro, as some degree of host specificity occurs with this pathogen (Chase et al. 1992). Some other Araceae species may be susceptible.


Impact score: A – indiscernible at the local level There are no known direct consequences of this pathogen on the natural or built environment.

Indirect


Impact score: C – minor significance at the district level Eradication would be difficult and would be reliant on early detection. Cultural practices such as care in selection of uninfected planting material would need to be adopted.

Domestic trade Impact score: B – minor significance at the local level Establishment of this pest in taro growing areas would possibly elicit controls on the movement of produce to prevent further spread.


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International trade

Impact score: B – minor significance at the local level Taro exports may be affected by restrictions on trade with countries that do not have pathovars of Xanthomonas associated with taro.


Impact score: C – minor significance at the district level Wild populations of taro exist in Western Australia, Northern Territory, Queensland and New South Wales (native in the Northern Territory, and naturalised elsewhere). These are likely to be infected and become reservoirs of the pathogen, which may then spread to surrounding crops. There are more than 40 species of native and naturalised Araceae in Australia, but no information is available on their susceptibility to this pathogen.


The unrestricted risk for Xanthomonas axonopodis pv. dieffenbachiae is: VERY LOW.


The unrestricted risk estimate for Xanthomonas axonopodis pv. dieffenbachiae of ‘very low’ achieves Australia’s ALOP. Therefore, specific risk management measures are not required for these pests.

Review of import conditions for fresh taro corms Pest risk assessment – Corm rot

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4.12 Corm rot Marasmiellus colocasiae A new disease of taro was reported in Aracê, in the highlands of Brazil’s Espírito Santo State, in 2005. The basidiomycete Marasmiellus colocasiae was isolated from diseased taro corms. This fungus has only recently been described (Capelari et al. 2010), so little information on this pathogen is currently available. The disease was reported to have a severe impact on crop production, resulting in 100 percent loss in an area of two hectares (Capelari et al. 2010). Fruiting bodies grow in clumps on the stems and corms of taro plants.

Marasmiellus colocasiae is characterised by large white or cream basidiocarps (mushrooms), with slightly decurrent lamellae, large basidiospores, variable cheilocystidia, well-developed caulocystidia and absent pleurocystidia and pileocystidia (Capelari et al. 2010). The pileus (mushroom cap) is around 11–46 mm across, and the stipe (stem) is 16–44 mm tall and 1.4–1.8 mm thick. Marasmiellus colocasiae has only been reported from this one location in eastern Brazil, and only in association with taro.

There is insufficient relevant scientific information to undertake an assessment of Marasmiellus colocasiae at this time. The assessment of quarantine risk and the need for phytosanitary measures will be reviewed if an application to import taro from any country where this pathogen is present is received. In the interim, imports of taro from Brazil will not be permitted.

Review of import conditions for fresh taro corms Pest risk assessment – Corallomycetella root rot

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4.13 Corallomycetella root rot Corallomycetella repens; Anamorph: Rhizostilbella hibisci Corallomycetella repens is a common saprotroph in tropical soils (Goos 1962) that can cause severe losses to woody crops when predisposing conditions arise, particularly poor aeration and waterlogging in the soil (Booth and Holliday 1973). When these conditions occur, it can be a serious pathogen in young crops of lime (Citrus aurantifolia), tea (Camellia sinensis) and rubber (Hevea brasiliensis) (Booth and Holliday 1973). It causes violet root rot of cacao (Theobroma cacao), root rot of pawpaw (Carica papaya), and stinking root disease of many tropical woody plants, including Camellia spp., Citrus spp., Coffea spp., Mangifera spp. and avocado (Persea americana) (Rossman et al. 1999). A record of this species in Western Australia as a mycorrhizal associate of an introduced orchid (Bonnardeaux et al. 2007) is considered doubtful on ecological grounds.

Corallomycetella repens produces conspicuous reddish to almost black fungal strands (rhizomorphs) that grow beneath the bark of its hosts. It is usually distinguished by its yellow-orange and reddish fruiting bodies (synnemata and perithecia) on exposed roots and lower stems, and by the yellowing and collapse of the canopy, accompanied by a sickly sour smell (Booth and Holliday 1973).

Corallomycetella repens is pantropical in distribution, and has been recorded in Asia, Africa, Central and South America and Oceania (Rossman et al. 1999; Farr and Rossman 2011; CMI 1968; Mycobank 2011).



The likelihood that Corallomycetella repens will arrive in Australia with the importation of fresh taro corms from any country where this pathogen is present is: VERY LOW. • Corallomycetella repens has only been reported on taro in French Polynesia (Hammes et

al. 1989) and the Malay Peninsula (Thompson and Johnston 1953). • This organism is primarily a saprotroph living in the soil, but it can be parasitic on roots of

trees and other plants in waterlogged tropical habitats (Booth and Holliday 1973). • The effects of Corallomycetella repens on taro are not known, but it is likely the fungus

would be easily recognised as it would produce conspicuous rhizomorphs and fruiting bodies, similar to those produced on woody plants (Rossman et al. 1999).

• Rhizomorphs on the surface of corms or stinking rot of the corms are likely to be obvious on infected fresh taro corms during harvesting and packing, and infected corms are unlikely to pass grading and be exported. Ascospores or conidia on the surface of the corms could escape detection.

• Only taro grown in wetland paddies is likely to be infected. In dryland situations, the fungus is usually saprotrophic and does not attack living plants.


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The likelihood that Corallomycetella repens will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country, is: MODERATE. • Corms will be distributed to many localities by wholesale and retail trade and by

individual consumers. • Consumers will carry small quantities of taro corms to urban, rural and natural localities.

Small amounts of corm waste could be discarded in these localities. • Taro corms affected by stinking rot are likely to become obvious during distribution and

any infected corms are likely to be discarded. Most discarded corms are likely to be disposed of in municipal tips where they will be covered.

• Corallomycetella repens is usually found as a saprotroph (Goos 1962) and corm waste is likely to be discarded in close proximity to organic matter on the surface of soil.

• A number of known hosts of Corallomycetella repens are present in Australia, many of them widespread and common such as avocado, citrus, mango and pawpaw (Booth and Holliday 1973; Seifert 1985).


The likelihood that Corallomycetella repens will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country where this pathogen is present, is: VERY LOW.


The likelihood that Corallomycetella repens will establish within Australia, based on a comparison of factors in the source and destination areas considered pertinent to its survival and reproduction, is: MODERATE. • Corallomycetella repens is primarily a saprotroph in tropical soils, but it can be parasitic

on roots of trees and other plants in waterlogged tropical habitats (Booth and Holliday 1973).

• For growth, Corallomycetella repens has a minimum temperature of 12 °C, an optimum 27–30 °C, and a maximum of 33 °C (Seifert 1985). This fungus is therefore more likely to establish in tropical areas.

• Lower temperatures in temperate areas of Australia may limit the ability of this fungus to establish in these areas.

• Corallomycetella repens requires waterlogged, anaerobic conditions for development of the rhizomorphs (Seifert 1985), which invade the cortex of plant hosts (Booth and Holliday 1973). Only limited parts of northern Australia are likely to present suitable habitat for establishment of the pathogenic form.


The likelihood that Corallomycetella repens will spread within Australia, based on a comparison of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of the pest, is: MODERATE. • If Corallomycetella repens became established, it would spread through adjacent similar

habitat, as it has a wide host range (Seifert 1985).


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• Corallomycetella repens is transmitted in both soil and water (Booth and Holliday 1973), and could be spread by movement of contaminated soil on machinery and harvested produce, or via water runoff following rain or irrigation.

• Climatic conditions (temperature, soil moisture) might limit its spread in temperate areas of Australia.

• Corallomycetella repens is likely to spread more widely in tropical areas of Australia.

4.13.4 Probability of entry, establishment and spread The likelihood that Corallomycetella repens will be imported as a result of trade in fresh taro corms from any country where this pathogen is present, be distributed in a viable state to susceptible hosts, establish and spread within Australia, is: VERY LOW.

4.13.5 Consequences Assessment of the potential consequences (direct and indirect) of Corallomycetella repens for Australia is: VERY LOW.


Direct


Impact score: C – minor significance at the district level Taro is only a minor host for Corallomycetella repens. Impacts are likely to be more severe on other crops, such as coffee, rubber and citrus (Rossman et al. 1999), but then only in waterlogged situations (Booth and Holliday 1973). Seifert (1985) identified 15 plant families with known hosts, and so a range of native flora is potentially susceptible to Corallomycetella repens.



Indirect


Impact score: B – minor significance at the local level Control is cultural, by avoiding soil waterlogging (Booth and Holliday 1973; Ecoport 2011).

Domestic trade Impact score: B – minor significance at the local level Infected taro would be unsaleable. Restrictions on movement of nursery stock of woody crops might be imposed to prevent spread.

International trade

Impact score: B – minor significance at the local level Infected taro would be unsaleable. Restrictions on movement of nursery stock of woody crops might be imposed to prevent spread.




The unrestricted risk for Corallomycetella repens is: NEGLIGIBLE.



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The unrestricted risk estimate for root rot of ‘negligible’ achieves Australia’s ALOP. Therefore, specific risk management measures are not required for this pest.

Review of import conditions for fresh taro corms Pest risk assessment – Black root rot

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4.14 Black root rot Rosellinia pepo Rosellinia pepo is a tropical root pathogen responsible for black root rot. Root diseases caused by Rosellinia spp. occur on a wide variety of commercially important crops, trees and ornamentals (ten Hoopen and Krauss 2006). Black root rot diseases caused by species of Rosellinia may be serious economic threats to woody plants, especially on recently deforested lands, due to their mechanism of spread. Their dissemination is by contact between infected and healthy roots and by fungal growth on the organic matter in the soil (Oliveira et al. 2008).

Rosellinia pepo is present in tropical areas in Central and South America, the West Indies, West Africa and Asia, although distribution is restricted. Australia does not currently import taro grown in these regions, but trade may occur in the future.



The likelihood that Rosellinia pepo will arrive in Australia with the importation of fresh taro corms from any country where this pathogen is present is: LOW. • Taro is only a minor host of Rosellinia pepo (CABI 2011). • Rosellinia pepo is present on the roots as greyish cobweb-like strands that become black

and coalesce into a woolly mass (ten Hoopen and Krauss 2006). Following infection, the roots and stem base are quickly surrounded by this mat of dark hyphae. This hyphal mat produces synnematal conidiophores, which produce large numbers of conidia (CABI 2011). The hyphae are visible to the naked eye on the surface of the roots and corms (CABI 2011) and would be obvious on fresh taro corms at harvest or during pre-export processing. Infected corms are unlikely to reach the export stream.

• Ascomata are only formed at a late stage once the plant tissues have been dead for some time (CABI 2011) and so contaminating ascospores are unlikely to be present on taro corms. The role that ascospores play in disease epidemiology is unclear (Oliveira et al. 2008).

• Rosellinia pepo is a soil-borne pathogen, and importation would be more likely if taro corms were contaminated with soil or other organic matter. Cleaning corms to remove soil and organic matter during commercial harvest and grading operations will reduce the presence of infectious material.


The likelihood that Rosellinia pepo will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country where this pathogen is present, is: MODERATE. • The infected corms are likely to be obvious during inspection and packing for distribution,

leading to infected corms being discarded early in the distribution chain. • Corms will be distributed to many localities by wholesale and retail trade and by

individual consumers. • Mycelia present on the corms would remain infectious if humidity was high during transit.


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• Small amounts of corm waste could be discarded in domestic compost. • Mycelial growth and transmission to new hosts could occur where infected corms were

discarded in proximity to organic matter and suitable plant hosts. • Rosellinia pepo is a tropical species, and it is unclear what effect cool conditions during

storage and transit of taro corms would have on pathogen viability. Storage of cultures at 5 °C on different substrates proved possible for up to two years (ten Hoopen and Krauss 2006).


The likelihood that Rosellinia pepo will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country where this pest is present, is: LOW.


The likelihood that Rosellinia pepo will establish within Australia, based on a comparison of factors in the source and destination areas considered pertinent to its survival and reproduction, is: MODERATE. • Rosellinia pepo is plurivorous, affecting many woody and sub-woody crops. Hosts,

including avocado, banana, breadfruit, coffee, lime, mangosteen and rubber (Oliveira et al. 2008) are present in many parts of Australia.

• Rosellinia pepo can survive on organic matter in the soil (Oliveira et al. 2008). • Root rot associated with Rosellinia spp. is often associated with high soil humidity, acid

soils and a high percentage of organic matter (ten Hoopen and Krauss 2006). Disease is less likely to establish in areas of low rainfall frequency, where little organic matter accumulation occurs and where there is low shade and uneven ground (Oliveira et al. 2008). Only parts of northern Australia are likely to present suitable habitats and conditions for establishment.


The likelihood that Rosellinia pepo will spread within Australia, based on a comparison of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of the pest, is: MODERATE. • Opportunistic soil-borne pathogens such as Rosellinia spp. are difficult to control once

they become established (ten Hoopen and Krauss 2006). • Dissemination is based on contact between infected and healthy roots, or by fungal growth

on organic matter in the soil (ten Hoopen and Krauss 2006). Rainwater can carry infected materials and plant debris throughout the soil (Oliveira et al. 2008).

• If the fungus did manage to establish in a suitable habitat, then it would spread into adjacent climatically similar habitat, as it possesses a wide host range.

• Climatic conditions (particularly temperature and humidity) would limit its spread as a pathogen to the northern parts of Australia.


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4.14.4 Probability of entry, establishment and spread The likelihood that Rosellinia pepo will be imported as a result of trade in fresh taro corms from any country where this pathogen is present, be distributed in a viable state to susceptible hosts, establish and spread within Australia, is: LOW.

4.14.5 Consequences Assessment of the potential consequences (direct and indirect) of Rosellinia pepo for Australia is: LOW.


Direct


Impact score: D – significant at the district level Taro is only a minor host for this pathogen. Impacts are likely to be more severe on other, more woody, crops, particularly coffee, as well as rubber, avocado, mangosteen and breadfruit, particularly in areas of high rainfall and soil moisture. It could be pathogenic on woody components of the native flora of the wet tropics.



Indirect


Impact score: B – minor significance at the local level Control is cultural, by avoiding soil waterlogging, increasing the soil pH and removing woody debris and all infected material (ten Hoopen and Krauss 2006).

Domestic trade Impact score: B – minor significance at the local level Infected taro would be unsaleable. Restrictions on movement of nursery stock of woody crops might be imposed to prevent spread.

International trade

Impact score: B – minor significance at the local level Infected taro would be unsaleable. Restrictions on movement of nursery stock of woody crops might be imposed to prevent spread.




The unrestricted risk for Rosellinia pepo is: VERY LOW.


The unrestricted risk estimate for Rosellinia pepo of ‘very low’ achieves Australia’s ALOP. Therefore, specific risk management measures are not required for this pest.

Review of import conditions for fresh taro corms Pest risk assessment – Taro leaf blight

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4.15 Taro leaf blight Phytophthora colocasiae Phytophthora colocasiae causes large lesions of the taro leaf lamina. In susceptible cultivars, it will also spread to the petioles and cause a rot of the petiole base and flower (Paiki 1996). It can also migrate to the corm or be transferred to the corm at harvest, causing a hard rot that may be difficult to detect until the corm is cut open (Erwin and Ribeiro 1996; Carmichael et al. 2008). During storage under high humidity, corms may develop brown lesions that coalesce to form a spongy hard rot, destroying the corm within 5–10 days (Jackson and Gollifer 1975; Jackson 1999; CABI 2011). When present with other pathogens, rots may be blue or black (Jackson and Gollifer 1975).

Sporangia are the most important survival structures of Phytophthora colocasiae (Quitugua and Trujillo 1998). They are readily disseminated from lesions on leaves by water splash (Onwueme 1999). The sporangia germinate and release zoospores that are also dispersed by splash or wind. Zoospores germinate readily under wet conditions and are the main propagules of the pathogen, but they are fragile and will die within 2–3 hours on sunny days in low humidity (Jackson 1999).

Phytophthora colocasiae is typically heterothallic, requiring the presence of two mating types, A1 and A2, for production of oospores. Most areas where Phytophthora colocasiae is present have either the A1 or A2 mating type only (Lin and Ko 2008). Oospores and chlamydospores have not been reported in naturally infected host tissues. However, self-fertile homothallic isolates of an A1/A2 type have been reported in Taiwan, which are able to produce oospores in live taro petiole tissue (Lin and Ko 2008).

Phytophthora colocasiae is thought to have originated in South East Asia, but is now widespread in many parts of the world where taro is grown (Gollifer et al. 1980; Tyson and Fullerton 2007). Its host range is largely restricted to Araceae, as well as rubber (Hevea brasiliensis), American ginseng (Panax quinquefolius), periwinkle (Vinca spp.) and betel (Piper betle) (McRae 1934; Gollifer et al. 1980; Erwin and Ribeiro 1996; CABI 2011).



The likelihood that Phytophthora colocasiae will arrive in Australia with the importation of fresh taro corms from any country where this pathogen is present is: HIGH. • The principal phytosanitary risk of introducing Phytophthora colocasiae is through the

introduction and vegetative propagation of infected material (Jackson 1999; CABI 2011). • Infection with Phytophthora colocasiae damages the leaves, reducing the size of the

corms (Vasquez 1990; Paiki 1996). Severely infected plants do not produce commercially acceptable corms.

• Sporangia on the leaves and petiole bases can release zoospores that are dispersed by water splash into the soil. These zoospores may be associated with soil adhering to poorly cleaned corms, or may enter the corm tissues at harvest through wounds when the leaves and suckers are removed (Jackson 1999).

• Sporangia or zoospores could be present in the petiole bases of imported taro corms.


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• Zoospores are the main propagules of the pathogen. They germinate readily in wet conditions (Quitugua and Trujillo 1998) but require ample moisture for infection and will die within 2–3 hours on sunny days if the humidity subsequently falls (Jackson 1999; Gollifer et al. 1980). However, zoospores may encyst under moisture stress (Quitugua and Trujillo 1998), enabling them to survive desiccation.

• Infective hyphae may also be present within the corms, which can develop into a storage rot under humid conditions (Gollifer et al. 1980; Jackson 1999). Phytophthora colocasiae may destroy an infected corm within 5–10 days of harvest (Jackson 1999). Infected corms may develop grey-brown to dark blue lesions that coalesce to form a spongy hard rot, destroying the corm completely within about eight days from harvest (CABI 2011).

• Oospores have not been reported in the field (Gollifer et al. 1980), but recent findings of homothallic isolates suggest that oospores are a possible survival structure and a natural source of genetic variation (Lin and Ko 2008). Quitugua and Trujillo (1998) have confirmed that chlamydospores form in soil, although they are not known to form in plants (Gollifer et al. 1980).

• Jackson and Gollifer (1975) reported difficulty in initiating rots using hyphal cultures alone, suggesting that infection of corms is mainly via sporangia and zoospores.

• Cleaning of taro corms and removal of all soil and leaf material would reduce the likelihood of infectious zoospores and zoosporangia being imported with the corms, but internal postharvest rot would not be affected.

• It is likely that some infested corms may escape detection, as postharvest rot caused by Phytophthora colocasiae is often not detectable until the corm is cut open (Erwin and Ribeiro 1996; Carmichael et al. 2008).


The likelihood that Phytophthora colocasiae will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country where this pathogen is present, is: MODERATE. • Corms carrying the pathogen may be distributed by wholesale and retail trade, and by


Small amounts of corm waste could be discarded in these localities. • Some corms will be distributed to areas where taro or other host plants grow. • Small amounts of corm waste could be discarded in domestic compost. • Corms with postharvest rot caused by Phytophthora colocasiae can be difficult to detect

unless the corms are cut open (Carmichael et al. 2008), but are likely to decay within 5–10 days of harvest (Jackson 1999). Infected corms discarded after arrival in Australia may contain viable hyphae.

• Under wet conditions, sporangia and zoospores may form on the surfaces of infected corm waste and be dispersed to hosts by water splash or wind.

• Sporangia and zoospores exposed to drying will quickly lose viability (Trujillo 1965). However, zoospores that entered the corm tissues during removal of leaves and suckers (Jackson 1999) or lodged in petiole bases, will be protected from drying and survive for longer periods (Gollifer et al. 1980).

• New infestations of Phytophthora colocasiae typically occur through direct transfer of the pathogen in infected or contaminated planting material.


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• Small corm taro will sprout readily from lateral buds in the corm and so may be propagated easily (Onwueme 1999). Large corm taro is traditionally marketed with a short tuft of petiole bases still attached to the corm, which can propagate from apical or lateral buds. If plants were to grow from infected taro corms or discarded corm waste, they are likely to be exposed to infection by Phytophthora colocasiae.

• Phytophthora colocasiae has a restricted host range. Its main host is taro, which is cropped commercially and grows in many parts of northern Australia in natural situations. Other hosts such as Alocasia macrorrhiza and other Araceae species are common garden plants in many parts of Australia.


The likelihood that Phytophthora colocasiae will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country where this pathogen is present, is: MODERATE.


The likelihood that Phytophthora colocasiae will establish within Australia, based on a comparison of factors in the source and destination areas considered pertinent to its survival and reproduction, is: HIGH. • Sporangia on wet leaves or moist soils will release short-lived zoospores to infect new

hosts (Quitugua and Trujillo 1998). • Nearby plants may become infected by these zoospores, which are dispersed by rain

splash or by wind-driven rain or dew (Gollifer et al. 1980; Jackson 1999; Onwueme 1999).

• Phytophthora colocasiae is present in regions with climatic conditions similar to those existing in some coastal parts of northern Australia.

• New infestation initiated by spores typically occurs via other infested plants in the vicinity, or from nearby crops. However, it is possible that spores present on trash and in soil (CABI 2011) might provide sufficient inoculum to initiate a new infection.

• Gollifer et al. (1980) reported that survival of sporangial inoculum in soil was typically less than two weeks. However, Quitugua and Trujillo (1998) studied survival of Phytophthora colocasiae and found it could survive in soil for more than three months. It is likely that zoospores encyst in response to dry conditions and are able to survive for considerable periods (Quitugua and Trujillo 1998).

• Sporangia germinate rapidly in wet soil to release zoospores (Gollifer et al. 1980; Quitugua and Trujillo 1998).

• Despite its ability to survive desiccation over considerable periods, viability of Phytophthora colocasiae in the absence of a host is estimated to be less than five months due to its lack of saprophytic ability (Quitugua and Trujillo 1998).

• While oospores and chlamydospores have not been reported in host tissue, Quitugua and Trujillo (1998) confirmed the formation of chlamydospores in soil.

• Phytophthora colocasiae may establish in domestic gardens or other situations where an infected corm is discarded in close proximity to growing taro or other host plants. However, infection via spores in trash is much less common than from spores originating from live infected plants. Survival of Phytophthora colocasiae zoosporangia in soil is


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ephemeral, and chlamydospores are prone to lysis by soil microorganisms (Quitugua and Trujillo 1998).


The likelihood that Phytophthora colocasiae will spread within Australia, based on a comparison of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of the pest, is: HIGH. • Phytophthora colocasiae is known to spread rapidly via water splash from infected leaves

to adjacent uninfected leaves (Onwueme 1999; Gollifer et al. 1980). It also spreads rapidly within plantations via water runoff.

• Water-borne spores could infect native and naturalized populations of taro and other aroids growing along watercourses.

• Wet weather is frequently cited as a factor in spread. Dew deposits on leaves provide micro-habitats for spore germination (Putter 1976).

• Longer distance dispersal by storms and wind-blown rain has also been documented (Putter 1976).

• Dispersal over longer distances by transport and planting of infected material, or transport of infested soil, is also possible (Carmichael et al. 2008).

• There are resistant cultivars of Colocasia esculenta, and cultural and chemical control has been attempted, but no control measure has proved to be fully effective against Phytophthora colocasiae (Onwueme 1999; Carmichael et al. 2008).

4.15.4 Probability of entry, establishment and spread The likelihood that Phytophthora colocasiae will be imported as a result of trade in fresh taro corms from any country where this pathogen is present, be distributed in a viable state to a susceptible host, establish and spread within Australia, is: MODERATE.

4.15.5 Consequences Assessment of the potential consequences (direct and indirect) of Phytophthora colocasiae is: MODERATE.


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Direct


Impact score: E – major significance at the district level Phytophthora colocasiae is a serious disease of taro. Yield reductions attributed to taro leaf blight in the Philippines ranged from 24.4 percent in resistant cultivars to 36.5 percent in susceptible cultivars (Vasquez 1990). Phytophthora colocasiae was largely responsible for a decline in taro production in parts of Papua New Guinea, Samoa and the Solomon Islands, especially in areas of high rainfall. Relatively minor economic damage is experienced in some countries such as the Philippines, Thailand and USA (Hawaii) (Onwueme 1999). The disease is exacerbated by high humidity, temperature and rainfall (Gollifer et al. 1980; Onwueme 1999) and is most damaging where rainfall exceeds 2500 mm and is distributed throughout the year (Jackson 1999). Most Australian taro is grown in dryland culture and requires irrigation to supplement natural rainfall. In much of the Australian subtropics, annual rainfall is less than 2000 mm, mostly falling over a period of six months. Under Australian climatic conditions of lower rainfall and humidity, combined with seasonal dry conditions over the winter months, the disease is unlikely to have the very high impacts observed elsewhere. Resistant cultivars are available in most major taro-growing countries, and switching to these would reduce the impact and slow the spread of the disease.


Impact score: A – indiscernible at the local level There are no known direct consequences of this pathogen on the natural or built environment

Indirect


Impact score: D – significant at the district level Eradication of Phytophthora colocasiae could be achieved by enforcing host free production in infested areas. The disease was introduced to the Island of Rota from Guam in 1967, causing producers to abandon the production of taro. When production was resumed in 1981, the disease was not observed (Quitugua and Trujillo 1998). Host free periods are considered effective in eradicating the disease (Quitugua and Trujillo 1998). However, eradication could be difficult if the pathogen became widely established. Cultural practices such as lower density planting and care in selection of uninfected planting material would need to be adopted (Onwueme 1999). Disease-resistant cultivars may not be as acceptable in the market place. Spraying with systemic or surface fungicides can be effective (Onwueme 1999), but fungicides could not be used along watercourses where wild populations of taro are typically found.


International trade

Impact score: B – minor significant at the local level The taro export trade from Australia is small. Restrictions on taro may be imposed by countries that do not have Phytophthora colocasiae. However, many taro producing countries have this disease and impacts on trade opportunities are likely to be limited.


Impact score: B – minor significance at the local level Given the relatively narrow host range affected by the pathogen, significant environmental and non-commercial impacts are unlikely to occur. The loss of some vegetation, as well as the use of fungicides to control Phytophthora colocasiae may have minor local effects.

4.15.6 Unrestricted risk estimate The unrestricted risk estimate for Phytophthora colocasiae is: MODERATE.


The unrestricted risk estimate for Phytophthora colocasiae of ‘moderate’ exceeds Australia’s ALOP, and specific risk management measures are required for this pest.

Review of import conditions for fresh taro corms Pest risk assessment – Taro pocket rot

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4.16 Taro pocket rot Phytophthora sp. Taro corms in Hawaii are affected by a slow-growing corm rot that forms small to medium sized cavities, particularly in the upper part of the corm. This rot was known for many years, but became particularly severe in the mid-1990s. Recent research has shown that it is caused by a homothallic (self-fertile) Phytophthora species that is still being characterised, and lacks a species epithet (CTAHR 2002). The Phytophthora sp. can only be isolated in the initial stages of infection. It attacks the corm near the base of the petiole and forms a small rot. Once the wound periderm forms, the Phytophthora sp. stops growing (SARE 2003). Secondary fungi (Rhizoctonia, Fusarium, Acremonium, etc.) invade the pocket and overgrow the Phytophthora sp. (SARE 2001). These secondary rots may later spread to the rest of the corm. Active rots caused by the Phytophthora sp. are never present in the lower two-thirds of the corm (SARE 2001).

Taro pocket rot has only been confirmed from Hawaii, so imports from other countries currently present negligible risk. However, rots caused by Phytophthora colocasiae can mimic pocket rot symptoms, so it may have been overlooked.



The likelihood that taro pocket rot will arrive in Australia with the importation of fresh taro corms from any country where this pest is present is: MODERATE. • Pocket rot affects taro corms. Cavities may only be apparent many months after infection

(CTAHR 2002). One to five cavities develop in the growing corm (Uchida et al. 2003). • Early stages of the disease may be difficult to discern (Uchida et al. 2003). The rots may

form under the skin with no sign of disease on the surface (Uchida et al. 2002). • Initial signs of infection are small rots near the base of the petiole (CTAHR 2002). The

Phytophthora sp. is only active for a brief period before other fungi invade the corm, making it difficult to isolate from pocket rots (SARE 2001).

• The presence of taro pocket rot reduces corm quality and yield. Heavily infected corms are therefore unlikely to enter the export chain, and if they do, are likely to be rejected during cleaning and packing.

• Taro pocket rot has only been found in Hawaii. Internal restrictions on movement of taro from pocket rot-infected areas have been in place for several years.

• New commercial cultivars recently introduced in Hawaii, which are resistant to taro leaf blight, have been found to be free of pocket rot (Trujillo et al. 2002). These plants were bred from Palauan cultivars, which have also been used in breeding Phytophthora-resistant cultivars for other Pacific countries.

• The main risk is from late-infected corms from areas not previously known to have the pathogen.


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The likelihood that taro pocket rot will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country where this pathogen is present, is: MODERATE. • Corms will be distributed to many localities by wholesale and retail trade and by


Small amounts of corm waste could be discarded in these localities. • Some corms will be distributed to areas where taro plants grow. • Small amounts of corm waste could be discarded in domestic compost. • The Phytophthora species responsible for pocket rot is extremely slow growing (CTAHR

2002) and symptoms of infection may not be apparent for some time. Corms with undetected late infections could be distributed in the retail chain.

• The effects of drying during storage and transport on viability of the pathogen are unknown. Oospores, which can be produced by this Phytophthora species (Uchida et al. 2002), are likely to remain viable for considerable periods in corms or any attached soil.


The likelihood that taro pocket rot will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country where this pathogen is present, is: LOW.

4.16.2 Probability of establishment The likelihood that taro pocket rot will establish in Australia, based on a comparison of factors in the source and destination areas considered pertinent to its survival and reproduction, is: LOW. • The Phytophthora species responsible for pocket rot can form thick walled oospores.

These permit it to survive for long periods in the soil without living hosts (Uchida et al. 2002).

• In the absence of host taro plants, Phytophthora species compete poorly with other microorganisms in the environment (Uchida et al. 2002; Quitugua and Trujillo 1998). Mycelia and asexual spores may be attacked by soil microbes including fungi, bacteria, protozoans and nematodes (Uchida et al. 2002).

• Hawaiian crops are mainly grown in paddy cultivation, while Australian crops are largely grown under dryland cultivation.

• The Phytophthora species that causes pocket rot may not be able to cause infections or establish under dryland conditions.

4.16.3 Probability of spread The likelihood that taro pocket rot will spread within Australia, based on a comparison of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of the pest, is: MODERATE. • Climatic conditions in northern Australia are similar to those in Hawaii. However,

Hawaiian crops are mainly grown in paddy cultivation, while Australian crops are largely


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grown under dryland cultivation. Lower water availability may reduce the suitability of Australian conditions for this pathogen to spread.

• Modes of transmission and infection have not been studied, but are likely to be similar to other Phytophthora species. Infected planting material is known to spread the disease (Uchida et al. 2002), and it is also likely to be spread via soil.

• Water-borne spores could infect wild and naturalized populations of taro and other aroids growing along watercourses.

• Soil spore numbers can increase with continuous taro cropping, increasing the likelihood of further spread (CTAHR 2002).

• Small initial outbreaks in Hawaii were not a cause for alarm, and it was tolerated for many years before suddenly becoming a problem in the 1990s. If there was a similar lack of attention paid to small outbreaks in Australia, the pathogen may spread before control measures could be imposed.

4.16.4 Probability of entry, establishment and spread The likelihood that taro pocket rot will be imported as a result of trade in fresh taro corms from any country where this pathogen is present, be distributed in a viable state to a susceptible host, establish and spread within Australia, is: VERY LOW.

4.16.5 Consequences Assessment of the potential consequences (direct and indirect) of taro pocket rot for Australia is: LOW.


Direct


Impact score: D – significant at the district level This is a serious pathogen of taro grown in flooded paddy situations in Hawaii. The pathogen may be less aggressive in Australia, where taro is not typically grown in flooded paddies. Wild taro growing in swampy environments would be susceptible to taro pocket rot. Other hosts have not been identified. Horticultural species (foliage plants) of Colocasia and Alocasia may be susceptible to infection.



Indirect


Impact score: C – minor significance at the district level Eradication is unlikely to be possible. Cultural practices such as fallowing, planting of alternative crops, and care in selection of uninfected planting material would need to be adopted. Disease resistant cultivars may not be as acceptable in the market place. Spraying with systemic or surface fungicides may be effective in controlling the pathogen, but add to costs.


International trade

Impact score: B – minor significance at the local level The taro export trade from Australia is small. Restrictions are likely for taro to countries that do not have this Phytophthora species.


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The unrestricted risk for the Phytophthora sp. responsible for taro pocket rot is: NEGLIGIBLE.


The unrestricted risk estimate for taro pocket rot of ‘negligible’ achieves Australia’s ALOP. Therefore, specific risk management measures are not required for this pest.

Review of import conditions for fresh taro corms Pest risk assessment – Pythium corm rot

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4.17 Pythium corm rot Pythium carolinianum Pythium rots affect both wetland and dryland taro, although mature corms are rarely attacked in dryland production (TaroPest 2008). Warm and stagnant water in paddy fields and poor field sanitation probably contribute to the high incidence of the pathogen (Ooka 1994). Pythium spp. are most abundant in wet or waterlogged soil and paddies where water circulation is poor. They have a wide host range but can also survive saprotrophically (TaroPest 2008). Infection usually first affects the fibrous roots. In wet (flooded) cultivation, the infection may then spread to the corm, producing a soft stinking rot.

Pythium root and corm rots are probably the most widely distributed diseases of taro (Ooka 1994), caused by various Pythium species that occur throughout the Pacific (Jackson and Gerlach 1985; Carmichael et al. 2008). Pythium carolinianum has been recorded on taro in Papua New Guinea and Hawaii (Farr and Rossman 2011). It is consistently associated with soft rotted taro corms in Hawaii, and is especially damaging under adverse growing conditions (Ooka and Yamamoto 1979). New Zealand has experimented with hot water dips as a postharvest pathogen mitigation measure, and initial results suggest that these may be effective against corm rots (Glassey 2006).


The likelihood that Pythium carolinianum will arrive in Australia with the importation of fresh taro corms from any country where this pathogen is present is: MODERATE. • Plants infected with Pythium spp. show early wilting and curling of leaves. Remaining

leaves are an unhealthy greyish blue-green, with pale yellow margins. Plants remain stunted, new leaf production is slow and corms are small (Jackson and Gerlach 1985). Such substandard corms are unlikely to be exported.

• Pythium carolinianum is associated with wetland taro rather than dryland taro. In wetland situations, Pythium root rots usually develop into corm rots where the interior of the corm is progressively transformed into a foul smelling soft mass (Jackson and Gerlach 1985).

• Initially, the decay is mostly restricted to small lateral roots, proceeding to extensive browning and rotting of the entire root system before the rot spreads to the corm (Jackson and Gerlach 1985), which usually decays from the base (Carmichael et al. 2008). Lesions appear on the corm surface in the early stages of corm infection (Carmichael et al. 2008).

• Certain soil conditions are necessary for the appearance of the disease in a destructive form, including high temperatures, abundant moisture, and low biological activity and poor physical condition of the soil (TaroPest 2008). Taro grown in acidic soils with low calcium levels has been identified as more susceptible to Pythium infection (Trujillo et al. 2002).

• Healthy corms may be infected at harvest or after harvest by Pythium fungi present on the corm surface via wounds made as leaves are detached (Jackson and Gerlach 1985). Postharvest rots usually manifest themselves rapidly. Losses of up to 20 percent have been reported within 10 days (Jackson and Gerlach 1985).


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• Such rots should be evident, and affected corms would be culled during harvesting or packing. Seriously infected corms, in which the disease has progressed to a corm rot, are likely to be detected before reaching the distribution stage.


The likelihood that Pythium carolinianum will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country where this pathogen is present, is: MODERATE. • Lightly infected corms, where the disease is still confined to the root tips, might escape

detection and be distributed, although most roots will have been removed prior to export. • Corms will be distributed to many localities by wholesale and retail trade and by


Small amounts of corm waste could be discarded in these localities. • Some corms will be distributed to areas where taro or other hosts grow. • Small amounts of corm waste could be discarded in domestic compost. • Zoospores can be carried in water to new hosts and are attracted to chemical exudates

from the root tips (Jackson and Gerlach 1985).


The likelihood that Pythium carolinianum will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country where this pathogen is present, is: LOW.

4.17.2 Probability of establishment The likelihood that Pythium carolinianum will establish in Australia, based on a comparison of factors in the source and destination areas considered pertinent to its survival and reproduction, is: MODERATE. • Related corm rot pathogens (e.g. Pythium aphanidermatum, Pythium middletonii, Pythium

myriotylum, Pythium splendens and Pythium vexans) are already established in Australia (Jackson and Gerlach 1985; CABI 2011) on a wide range of hosts (Simmonds 1966; Cook and Dube 1989; Shivas 1989). These pathogens are principally associated with dryland taro.

• Pythium carolinianum is primarily associated with wetland and irrigated taro. Most taro in Australia is cultivated under dryland conditions. However, establishment would be possible under some irrigation conditions. Naturalised or native taro growing along watercourses or in swampy areas would be most susceptible to infection by Pythium carolinianum.

• Pythium species usually have broad host ranges, and can survive as saprobes on trash from previous crops in the field (Jackson and Gerlach 1985).


The likelihood that Pythium carolinianum will spread, based on a comparison of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of the pest, is: HIGH.


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• Spread occurs via zoospores that are carried in irrigation water and are attracted to chemical exudates from the root tips (Jackson and Gerlach 1985). Pythium species can also be transferred to new areas on infected vegetative planting material.

• While Pythium carolinianum is known to infect taro under favourable conditions, it is a less aggressive pathogen than other species such as Pythium myriotylum (Liloqula et al. 1993) that are more commonly associated with corm rot.

• Irrigation, high rainfall or paddy cultivation will assist rapid local spread. Use of infected corm pieces or suckers will assist longer distance spread.

• Temperatures above 25 °C are required for most Pythium species to grow in the soil and in infected plants. Below this temperature, little disease may result even if other factors are optimal (Jackson and Gerlach 1985). Taro planting material (petioles) inoculated with Pythium carolinianum (zoospores and chopped mycelia) and incubated at 35 °C for three weeks developed root lesions and corm rot (Ooka and Yamamoto 1979). Appreciable rot was evident 72 hours after inoculation at 35 °C and 40 °C, while very little rot was observed at 30 °C and 25 °C (Ooka and Yamamoto 1979). Inoculation with Pythium carolinianum at 20 °C did not result in development of root lesions or corm rot, although the pathogen was recovered from the roots (Ooka and Yamamoto 1979). Spread is therefore likely to be limited to the warmer, wetter areas of northern Australia.

4.17.4 Probability of entry, establishment and of spread

The likelihood that Pythium carolinianum will be imported as a result of trade in fresh taro corms from any country where this pathogen is present, be distributed in a viable state to a susceptible host, establish and spread within Australia, is: LOW.

4.17.5 Consequences Assessment of the potential consequences (direct and indirect) of Pythium carolinianum for Australia is: LOW.


Direct


Impact score: D – significant at the district level Pythium spp. involved in root rots have a broad host range and may affect other crops. Pythium carolinianum has been reported as pathogenic on the roots of cotton (Abdelzaher and Elnaghy 1998), turfgrass (Abad et al. 1994) and Myriophyllum brasiliense (Bernhardt and Duniway 1984). Water plants such as Limnophila, Potamogeton and Myriophyllum have been reported as susceptible to infection by Pythium spp. under some circumstances. Australia has a substantial number of species of these genera and their susceptibility to infection by Pythium spp. has not been tested.


Impact score: B – minor significance at the local level Pythium carolinianum is known to kill mosquitoes (Su et al. 2001).


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Indirect


Impact score: C – minor significance at the district level Once soil becomes contaminated by Pythium spp., control is difficult and expensive (Jackson and Gerlach 1985). Resistant varieties of taro are known from many Pacific islands, although fully non-susceptible varieties are not reported (Jackson and Gerlach 1985; Trujillo et al. 2002). High levels of soil calcium are associated with low levels of Pythium rot (Trujillo et al. 2002), and higher fertiliser levels (and more vigorous growth) also reduce the effects of Pythium attack (Jackson and Gerlach 1985). Prevention of waterlogging and not growing in stagnant water are the most effective preventative measures. A number of other, more aggressive, Pythium species are already in Australia, and existing measures to control these pathogens will also be effective against Pythium carolinianum.


International trade

Impact score: B – minor significance at the local level The taro export trade from Australia is small. Restrictions are possible for exports of taro to countries that do not have Pythium carolinianum.


Impact score: B – minor significance at the local level The introduction of an additional Pythium species to Australia could result in localised ecological changes, particularly in swampy areas, where vegetation is severely affected by rots.


The unrestricted risk for Pythium carolinianum is: VERY LOW.


The unrestricted risk estimate for Pythium carolinianum of ‘very low’ achieves Australia’s ALOP. Therefore, specific risk management measures are not required for this pest.

Review of import conditions for fresh taro corms Pest risk assessment – Colocasia bobone disease virus

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4.18 Colocasia bobone disease Colocasia bobone disease virus (CBDV) CBDV is a rhabdovirus that has been identified only in Colocasia esculenta (Brunt et al. 1996). The virus is transmitted by the planthoppers Tarophagus proserpina, Tarophagus colocasiae and Tarophagus persephone (QUT 2003; CABI 2011). CBDV causes bobone disease and probably also causes the more severe alomae disease (James et al. 1973). Plants with bobone disease are stunted, often severely, and have thickened, malformed and brittle leaves, and may have galls on their petioles and larger veins. Typically, only a few leaves are affected by bobone disease and healthy leaves are produced after several weeks in an apparent recovery (Cook 1978; Carmichael et al. 2008). Initially, alomae disease may be indistinguishable from bobone disease, but the plants with alomae develop chlorosis and/or progressive necrosis. Some collapse, and all finally rot and die (Cook 1978; QUT 2003). After plants recover from bobone disease, the symptoms may recur (Carmichael et al. 2008), indicating that the plants still harbour the virus. Some plants infected with CBDV do not develop bobone or alomae disease, but instead have milder symptoms, or may be nearly symptomless (Shaw et al. 1979; Revill et al. 2005a).

There is strong evidence that CBDV causes bobone disease and considerable evidence that it is required for alomae disease. However, tests have not been done to confirm the etiology, and four other viruses have been detected in plants with bobone and alomae diseases: Dasheen mosaic virus (DsMV), Taro bacilliform virus (TaBV), Taro vein chlorosis virus (TaVCV) and taro reovirus (TaRV) (James et al. 1973; Shaw et al. 1979; Revill et al. 2005a). It is likely that one or both diseases result from synergistic interactions between two or more of the viruses when they co-infect taro plants (Bos 1999; Revill et al. 2005a). It has been proposed that co-infections of CBDV and TaBV produce alomae disease, but the evidence is weak at present (James et al. 1973; Revill et al. 2005a). The possibility that DsMV, TaRV or TaVCV are involved in alomae disease, probably when co-infecting with CBDV, cannot be discounted (Revill et al. 2005a). Cultivar susceptibilities may also be significant (Cook 1978; Carmichael et al. 2008).

Tests of taro grown in Pacific Island countries have identified CBDV only in Papua New Guinea and the Solomon Islands (Pearson et al. 1999; Revill et al. 2005a; Davis et al. 2005; Davis et al. 2006). CBDV probably does not occur in other countries. The risk presented by CBDV in taro from Papua New Guinea and the Solomon Islands was assessed.



The likelihood that colocasia bobone disease virus will arrive in Australia with the importation of fresh taro corms from any country where this pest is present is: HIGH. • CBDV is widespread in Papua New Guinea and the Solomon Islands (Shaw et al. 1979;

Revill et al. 2005a; Carmichael et al. 2008). • CBDV infects systemically and is likely to be present in some or all corms from infected

plants (James et al. 1973; Zettler et al. 1989; Carmichael et al. 2008). • CBDV is associated with the bobone and alomae diseases, the symptoms of which include

chlorosis, necrosis, leaf malformation, stunting and plant death (Cook 1978; QUT 2003; Carmichael et al. 2008). Plants affected by alomae disease are unlikely to produce


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commercially acceptable corms. Bobone disease may reduce corm yields by 25 percent (Gollifer et al. 1978; Cook 1978).

• Some taro plants may be infected by CBDV, but show few, if any, symptoms (Shaw et al. 1979; Revill et al. 2005a).

• Taro plants will recover from bobone disease, but may develop the disease again (Carmichael et al. 2008), indicating that they still harbour the virus.

• The condition of corms from infected plants has not been reported. It is highly likely that some infected corms will be indistinguishable from uninfected corms, so some corms carrying the virus are likely to escape detection.


The likelihood that colocasia bobone disease virus will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country where this pathogen is present, is: HIGH. • Imported corms are intended for human consumption. Corms will be distributed to many

localities by wholesale and retail trade and by individual consumers. • Individual consumers will carry small quantities of taro corms to urban, rural and natural

localities. • Small amounts of corm waste could be discarded in these localities. • Some corms will be distributed to areas where taro or other aroid species grow. • Small amounts of corm waste could be discarded into domestic compost. • Discarded corm waste of infected small corm taro may sprout and develop into infected

plants. • Some infected corms of small corm taro may be planted for domestic cultivation instead

of being consumed and develop into infected plants.


The likelihood that colocasia bobone disease virus will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country where this pathogen is present, is: HIGH.

4.18.2 Probability of establishment The likelihood that colocasia bobone disease virus will establish within Australia, based on a comparison of factors in the source and destination areas considered pertinent to its survival and reproduction, is: MODERATE. • If a volunteer taro plant grows from a corm carrying CBDV, it may be infected with the

virus. • Small corm taro will sprout readily from lateral buds in the corm and so may be

propagated easily (Onwueme 1999). Large corm taro is traditionally marketed with a short tuft of petiole bases still attached to the corm, which can propagate from apical or lateral buds. New plants are likely to be infected with the virus.

• Wild taro mainly propagates vegetatively with lateral buds giving rise to daughter corms (Purseglove 1972; Onwueme 1999).


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• Colocasia esculenta is considered to be native in the Northern Territory, and naturalised in Western Australia, Queensland, New South Wales, and on Christmas Island, Norfolk Island and Lord Howe Island (CHAH 2009).

• Colocasia esculenta was included in a list of the 200 most invasive plants in South East Queensland by Batianoff and Butler (2002). Hicks and Nguyen (2004) cautioned about disposal of waste corms of the eddoe (var. antiquorum) type, noting that the plants have the potential to become an invasive weed species.

4.18.3 Probability of spread The likelihood that colocasia bobone disease virus will spread within Australia, based on a comparative assessment of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of the pest, is: HIGH. • The planthoppers Tarophagus persephone (syn. Tarophagus proserpina australis) and

Tarophagus colocasiae are probably the vectors that spread CBDV (Shaw et al. 1979; Brunt et al. 1996; CABI 2011).

• Tarophagus colocasiae is found on wild taro in Far North Queensland and the islands of the Torres Strait, while Tarophagus persephone has a wider distribution through northern Queensland and the Northern Territory (Matthews 2003; AICN 2011; CABI 2011).

• CBDV may spread if Tarophagus planthoppers feed on an infected volunteer plant and then move on to feed on healthy taro plants.

• When vectors are present, the virus can infect over 90 percent of a population (Gollifer et al. 1978).

• Sometimes plants infected with CBDV do not have obvious symptoms (Shaw et al. 1979; Revill et al. 2005a).

• Infection of hosts and spread of the virus may initially go undetected. • If bobone disease occurs in a commercial taro crop, symptoms will become obvious and

remedial action is likely to be initiated. • Destruction of infected taro plants is likely to prevent the virus from spreading, as long as

Tarophagus spp. are not present (Zettler et al. 1989). • Insecticides may be effective in stopping the spread of the virus by Tarophagus spp.

(Gollifer et al. 1978; QUT 2003).

4.18.4 Probability of entry, establishment and spread The overall likelihood that colocasia bobone disease virus will be imported as a result of trade in fresh taro corms from any country where this pathogen is present, be distributed in a viable state to a susceptible host, establish and spread within Australia, is: MODERATE.

4.18.5 Consequences Assessment of the potential consequences (direct and indirect) of colocasia bobone disease virus is: LOW.


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Direct


Impact score: D – significant at the district level Planthoppers that could spread the virus are present in northern Queensland and the Northern Territory (Matthews 2003), and these areas could be affected if an incursion occurred. CBDV causes bobone disease of taro, the symptoms of which include severe stunting and leaf malformation. Corm production may be reduced by about 25 percent by bobone disease (Gollifer et al. 1978; Cook 1978). CBDV probably also causes alomae disease when co-infecting taro with TaBV, or perhaps one of three other virus species (Revill et al. 2005a; Carmichael et al. 2008). TaBV is present in Australia, so the conditions for the emergence of alomae disease may exist. Alomae disease kills taro plants and can completely destroy taro crops (Gollifer et al. 1978; Shaw et al. 1979). Cultivation of some taro cultivars ceased in the Solomon Islands as a result of alomae disease (Gollifer et al. 1978). Native populations of taro in the Northern Territory may be susceptible to CBDV and may decline if the virus becomes established and is spread. It is not known if the virus may infect other plant species.


Impact score: A – indiscernible at the local level There are no known direct consequences of this virus on the natural or built environment.

Indirect


Impact score: D – significant at the district level If CBDV becomes established in Australia, eradication or control measures would likely be initiated. Measures would probably involve culling and quarantine, growing resistant cultivars, and spraying with insecticides. Many cultivars are susceptible to alomae disease, although some are resistant (Gollifer et al. 1978). Resistant cultivars may still suffer losses from bobone disease (Cook 1978). Naturalised and native populations of taro are likely to become reservoirs of the virus in the areas they occur in Australia.

Domestic trade Impact score: B – minor significance at the local level If CBDV becomes established in Australia, it is likely to result in interstate trade restrictions on taro, as well as potential loss of markets and significant industry adjustment.

International trade

Impact score: B – minor significance at the local level The taro export trade from Australia is small. However, the presence of CBDV in Australia may lead to prohibition of exports to countries free of CBDV.


Impact score: A – indiscernible at the local level CBDV is unlikely to have any indirect effects on the environment.


The unrestricted risk for colocasia bobone disease virus is: LOW.


The unrestricted risk estimate for colocasia bobone disease virus of ‘low’ exceeds Australia’s ALOP, and specific risk management measures are required for this pest.

Review of import conditions for fresh taro corms Pest risk assessment – Dasheen mosaic virus

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4.19 Dasheen mosaic French Polynesian strain of Dasheen mosaic virus (FP-DsMV) Dasheen mosaic virus (DsMV) is a potyvirus that infects a wide range of commercially important Araceae, both edible and ornamental, and has a worldwide distribution (Zettler and Hartman 1987; Brunt et al. 1996; Elliott et al. 1997; Simone and Zettler 2009). The virus is present in most taro-growing regions, including Australia (Zettler and Hartman 1987; Zettler et al. 1989).

The symptoms of taro plants infected with DsMV are usually limited; the leaves have chlorotic mosaic or feather-like patterns and may be slightly malformed (Brunt et al. 1996; Nelson 2008).

A strain of DsMV, known as FP-DsMV, has been reported in taro in French Polynesia. Little is known about FP-DsMV, but incidental information supports the report. This strain is considered atypical because it severely distorts and stunts the leaves and some leaves are reduced to strap-like structures without leaf blades (Carmichael et al. 2008). Taro plants infected with ‘typical-DsMV’ strains usually show symptoms on two or three leaves and then recover to produce apparently healthy leaves (Nelson 2008). However, plants infected with FP-DsMV often do not recover (Carmichael et al. 2008). Differences between taro varieties probably influence symptoms, but may not account for the more severe symptoms caused by FP-DsMV. In field trials, plants of one taro variety infected with typical strains of DsMV were stunted, whereas plants from three other varieties were unaffected (Jackson et al. 2001).

Other DsMV strains can cause severe disease in other Aracaea, with symptoms including stunting and severe deformity, and with substantial yield losses (Zettler and Hartman 1987; Nelson 2008). Isolates of the virus obtained from Asia and Oceania are highly diverse (Gibbs et al. 2008a) and isolates from Vanilla tahitensis from the Cook Islands and French Polynesia are genetically and phenotypically distinct from other DsMV isolates (Farreyrol et al. 2006). Furthermore, potyviruses mutate at a relatively high rate (Gibbs et al. 2008b).

DsMV has been detected in the leaf laminae, petiole and corm tissue of taro (Hu et al. 1995). The virus has been widely distributed in planting stock, as it spreads where plants are grown from corms, cuttings or bulbs, and may be spread on contaminated pruning tools (Zettler and Hartman 1987; Nelson 2008). DsMV is also transmitted in a non-persistent manner by the aphids Myzus persicae, Aphis craccivora and Aphis gossypii.

FP-DsMV has only been reported in taro from French Polynesia. FP-DsMV probably does not occur in other countries. The risk presented by FP-DsMV in taro corms from French Polynesia was assessed.



The likelihood that the French Polynesian strain of Dasheen mosaic virus will arrive in Australia with the importation of fresh taro corms from any country where this pest is present is: MODERATE. • The geographic distribution of plants infected with FP-DsMV within French Polynesia is

not known.


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• Taro plants infected by FP-DsMV are stunted and have severely distorted leaves (Carmichael et al. 2008). Leaves probably also develop mosaic and feathering patterns. The leaves of some infected plants are reduced to strap-like structures without leaf blades (Carmichael et al. 2008).

• It is reported that plants infected with FP-DsMV often do not recover (Carmichael et al. 2008). However, a few plants may recover and appear healthy.

• It may be difficult to visually identify all plants infected with FP-DsMV. Plants infected with typical-DsMV strains may produce asymptomatic leaves (Nelson 2008) and symptoms may occur intermittently and vary seasonally (Hu et al. 1995).

• It is not known if plants infected with FP-DsMV would produce marketable corms. • The virus is present in the corms of plants infected with other DsMV strains (Zettler and

Hartman 1987; Hu et al. 1995; Nelson 2008). Hence, if corms are produced, it is likely FP-DsMV will be present in corms.

• FP-DsMV is probably transmitted by aphids. Plants may be infected by aphids after they have produced corms, and the virus may subsequently spread to the corms.

• The condition of corms that are produced from infected plants has not been reported. Infected plants may not produce commercially acceptable corms.

• It is possible that if infected corms are harvested, some may be indistinguishable from uninfected corms, so corms carrying the virus could escape detection and be exported to Australia.


The likelihood that the French Polynesian strain of Dasheen mosaic virus will be distributed in Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country, is: HIGH. • Imported corms are intended for human consumption. Corms will be distributed to many

localities by wholesale and retail trade and by individual consumers. Some corms will be distributed to areas where taro or other aroid species grow.

• If infected corms are imported, they are very likely to be distributed. • Consumers could discard small amounts of corm waste in urban, rural and natural

localities. Small amounts of corm waste could be discarded in domestic compost. • Discarded corm waste of infected small corm taro may sprout and develop into infected




The likelihood that the French Polynesian strain of Dasheen mosaic virus will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country, is: MODERATE.

4.19.2 Probability of establishment The likelihood that the French Polynesian strain of Dasheen mosaic virus will establish within Australia, based on a comparison of factors in the source and destination areas considered pertinent to its survival and reproduction, is: HIGH.


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• DsMV has already established in Australia, so it is likely that other strains of the virus such as FP-DsMV would have the ability to establish.

• If a volunteer taro plant grows from a corm carrying FP-DsMV, the plant is likely to be infected with the virus.

• Small corm taro will sprout readily from lateral buds in the corm, and so may be propagated easily (Onewueme 1999). Large corm taro is more difficult to propagate. New plants are likely to be infected with the virus.


• Colocasia esculenta was included in a list of the 200 most invasive plants in South East Queensland by Batianoff and Butler (2002). Hicks and Nguyen (2004) cautioned about disposal of waste corms of small corm taro, noting that the plants have the potential to become an invasive weed species.

• DsMV is established where plants are grown from corms, cuttings or bulbs, and may be spread on contaminated pruning tools (Nelson 2008; Zettler and Hartman 1987).

4.19.3 Probability of spread The likelihood that the French Polynesian strain of Dasheen mosaic virus will spread within Australia, based on a comparison of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of the pest, is: HIGH. • The aphids Myzus persicae, Aphis craccivora and Aphis gossypii are vectors of typical-

DsMV strains and are present in Australia (CABI 2011). FP-DsMV is probably transmitted by these same aphid species.

• FP-DsMV may spread if a vector aphid feeds on an infected volunteer plant and then feeds on healthy taro plants.

• The leaves of plants infected with FP-DsMV are severely distorted and stunted (Carmichael et al. 2008), so infection of a commercial crop is likely to be detected.

• Infected plants in a domestic garden may not be detected. • Infection of wild taro is likely to go undetected. • Infection of ornamental aroids by other DsMV strains can be controlled by quarantine and

integrated pest management, but it may not be economically feasible to implement such measures for taro production (Zettler and Hartman 1987; Jackson et al. 2001; Carmichael et al. 2008).

• Other DsMV strains can spread rapidly, with more than 50 percent of virus-free plants in trials being infected in 3–10 months (Jackson et al. 2001).

• Very high incidences of other DsMV strains have been reported in Colocasia spp. and in many countries (Zettler and Hartman 1987).

• FP-DsMV may spread to the same extent as other strains of DsMV, and it may be difficult to control.

• FP-DsMV may spread to naturalised and native populations of taro.

4.19.4 Probability of entry, establishment and spread The likelihood that the French Polynesian strain of Dasheen mosaic virus will be imported as a result of trade in fresh taro corms from any country where this pathogen is present, be


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distributed in a viable state to a susceptible host, establish and spread within Australia, is: MODERATE.

4.19.5 Consequences Assessment of the potential consequences (direct and indirect) of the French Polynesian strain of Dasheen mosaic virus is: LOW.


Direct


Impact score: D – significant at the district level Taro is produced commercially in New South Wales, Queensland and the Northern Territory. Plants infected with FP-DsMV have severely distorted and stunted leaves and often do not recover (Carmichael et al. 2008). In field trials, plants of one taro variety infected with typical strains of DsMV were stunted and yields were reduced by about 50 percent (Jackson et al. 2001). FP-DsMV probably causes greater yield losses than typical DsMV strains. If FP-DsMV were to establish and spread, it would probably have a major impact on the taro industry, and possibly also on the ornamental aroid foliage industry. Yields are likely to be substantially reduced. Data on the range of hosts that might be infected by FP-DsMV was not found. The host range of FP-DsMV may be similar to that of typical DsMV strains. Other DsMV strains naturally infect species from 14 Araceae genera: Aglaonema, Alocasia, Amorphophallus, Anthurium, Arisaema, Caladium, Colocasia, Cryptocoryne, Cyrtosperma, Dieffenbachia, Philodendron, Spathiphyllum, Xanthosoma and Zantedeschia (Zettler and Hartman 1987; CABI 2011). Australia has over 40 native and naturalised aroids, some of which may be susceptible to FP-DsMV, and most grow within the endangered area. Three Typhonium species, Typhonium jonesii, Typhonium mirabile and Typhonium taylori, are listed as endangered (EPBC 1999). There is a possibility that FP-DsMV may infect these endangered species.


Impact score: C – minor significance at the district level Taro has been recorded in the Goyder catchment and on the Walker River in the Arafura Wetlands, which is on the Register of the National Estate. Wild taro may be a significant plant in wetlands in the Northern Territory, and the establishment of the virus may result in changes to some wetland ecosystems.

Indirect


Impact score: C – minor significance at the district level Infection of ornamental aroids by other DsMV strains is controlled by tissue culture, quarantine and integrated pest management, but it may not be economically feasible to implement such measures for taro production (Zettler and Hartman 1987; Nelson 2008; Carmichael et al. 2008). Changing the varieties of taro that are cultivated may control the disease if FP-DsMV becomes established (Jackson et al. 2001).

Domestic trade Impact score: B – minor significance at the local level If FP-DsMV becomes established in Australia interstate trade of taro and some aroid ornamental plants may be restricted, and this may lead to the potential loss of markets and some industry adjustment.

International trade

Impact score: B – minor significance at the local level The taro export trade from Australia is small. Restrictions are possible for exports of taro to countries that do not have this strain of DsMV.




The unrestricted risk for the French Polynesian strain of Dasheen mosaic virus is: LOW.


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The unrestricted risk estimate for FP-DsMV of ‘low’ exceeds Australia’s ALOP. Therefore, specific risk management measures are required for this pest.

Review of import conditions for fresh taro corms Pest risk assessment – Taro reovirus

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4.20 Taro reovirus Taro reovirus (TaRV) TaRV is a reovirus that probably belongs in the Oryzavirus genus (Devitt et al. 2001). It has been detected in taro plants with bobone disease and in taro plants with alomae disease. Although it is unlikely that the virus is associated with bobone disease, it is possible that it is involved in alomae disease (Revill et al. 2005a). When sensitive tests were done, TaRV was detected in five out of six plants with alomae disease (Revill et al. 2005a). Previous investigations of plants with alomae disease may not have detected TaRV because a test was not available (Shaw et al. 1979; Revill et al. 2005a). Tests have not been done to confirm the etiology of alomae disease and four other viruses have been detected in plants with the disease: colocasia bobone disease virus (CBDV), Dasheen mosaic virus (DsMV), Taro bacilliform virus (TaBV) and Taro vein chlorosis virus (TaVCV) (James et al. 1973; Shaw et al. 1979; Revill et al. 2005a). Infection by CBDV is thought to be the primary cause. It has been proposed that the disease is produced by co-infection of CBDV with another virus, but the evidence is weak at present (James et al. 1973; Shaw et al. 1979; Revill et al. 2005a).

Plants with alomae disease are stunted and malformed. They develop chlorosis and/or progressive necrosis, some collapse, and all finally rot and die (Cook 1978; QUT 2003).

TaRV has been identified only in Colocasia esculenta and only in plants infected with at least one other virus (Devitt et al. 2001; Revill et al. 2005a). Some plants with TaRV did not have bobone disease or alomae disease, but their condition was not reported. Little is known about TaRV. It is not known if TaRV infects other plant species or how the virus is transmitted (Revill et al. 2005a). Plant-infecting reoviruses are transmitted by planthoppers (Delphacidae) or leafhoppers (Cicadelidae) (Fauquet et al. 2005). TaRV is likely to be transmitted by such insects.

Tests of taro grown in Pacific Island countries have identified TaRV only in Papua New Guinea, the Solomon Islands and Vanuatu (Revill et al. 2005a; Davis et al. 2005; Davis et al. 2006). TaRV probably does not occur in other countries.



The likelihood that taro reovirus will arrive in Australia with the importation of fresh taro corms from any country where this pest is present is: MODERATE. • TaRV appears to be widespread in the Solomon Islands and Vanuatu, and the virus is

present in Papua New Guinea (Revill et al. 2005a). • TaRV probably infects systemically and is likely to be present in some or all corms from

infected plants. • Whereas most reoviruses found in plants infect hosts systemically, some do not. For

example, Nilaparvata lugens reovirus may not replicate in plants, but is probably introduced by infected planthoppers feeding on the plants (Nakashima and Noda 1995; Fauquet et al. 2005). Hence, by analogy, there is a small possibility that TaRV does not replicate in taro.


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• TaRV may be associated with alomae disease (Revill et al. 2005a). The symptoms of alomae include stunting, chlorosis, necrosis, leaf malformation and plant death (Carmichael et al. 2008; Cook 1978; QUT 2003).

• Plants with alomae disease are unlikely to produce corms. • TaRV was detected in plants from Vanuatu that did not have alomae disease, but were

infected with other viruses (Revill et al. 2005a). The condition of the plants was not reported.

• Some taro infected by TaRV may show few, if any, symptoms. • The condition of corms from infected plants has not been reported. It is highly likely that

some infected corms will be indistinguishable from uninfected corms, so corms carrying the virus are likely to escape detection.

• Taro corms infected with TaRV could be imported.


The likelihood that taro reovirus will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country, is: HIGH. • Imported corms are intended for human consumption. Corms will be distributed to many

localities by wholesale and retail trade and by individual consumers. • If infected corms are imported, they are very likely to be distributed. • Consumers will carry small quantities of taro corms to urban, rural and natural localities.

Small amounts of corm waste could be discarded in these localities. • Some corms will be distributed to areas where taro or other aroid species grow. • Small amounts of corm waste could be discarded in domestic compost. • Discarded corm waste of infected small corm taro may sprout and develop into infected




The likelihood that taro reovirus will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country, is: MODERATE.

4.20.2 Probability of establishment The likelihood that taro reovirus will establish within Australia, based on a comparison of factors in the source and destination areas considered pertinent to its survival and reproduction, is: MODERATE. • TaRV has become established in a small number of Pacific Island countries. • If a volunteer taro plant grows from a corm carrying TaRV, the plant may be infected with

the virus. • Small corm taro will sprout readily from lateral buds in the corm, and so may be

propagated easily (Onewueme 1999). Large corm taro is more difficult to propagate. New plants are likely to be infected with the virus.



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• Colocasia esculenta was included in a list of the 200 most invasive plants in South East Queensland by Batianoff and Butler (2002). Hicks and Nguyen (2004) cautioned about disposal of waste corms of the eddoe (var. antiquorum) type, noting that the plants have the potential to become an invasive weed species.

4.20.3 Probability of spread The likelihood that taro reovirus will spread within Australia, based on a comparative assessment of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of the pest, is: MODERATE. • TaRV probably belongs in the Oryzavirus genus of plant-infecting reoviruses (Devitt et al.

2001). • Plant-infecting reoviruses are transmitted by planthoppers (Delphacidae) or leafhoppers

(Cicadelidae) (Fauquet et al. 2005). • The planthoppers Tarophagus persephone and Tarophagus colocasiae occur in

Queensland and the Northern Territory on wild taro (Matthews 2003; AICN 2011; CABI 2011).

• Tarophagus spp. planthoppers may be vectors of TaRV. • TaRV may spread if a vector arthropod feeds on an infected volunteer plant and then feeds

on healthy taro plants. • If alomae disease occurs in a commercial taro crop, symptoms will become obvious and

remedial action is likely to be triggered. • Insecticides may be effective at stopping the spread of the virus by planthoppers or

leafhoppers. • If the virus is detected in a crop, destruction of the taro plants is likely to prevent the virus

from spreading, as long as no vector is present. • TaRV may spread to naturalised and native populations of taro.

4.20.4 Probability of entry, establishment and spread The overall likelihood that taro reovirus will be imported as a result of trade in fresh taro corms from any country where this pathogen is present, be distributed in a viable state to a susceptible host, establish and spread within Australia, is: LOW.

4.20.5 Consequences Assessment of the potential consequences (direct and indirect) of taro reovirus is: LOW


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Direct


Impact score: D – significant at the district level Planthoppers that might spread TaRV are present in Queensland and the Northern Territory, so those areas could be affected if an incursion occurred. TaRV may initiate alomae disease when co-infecting taro with CBDV. CBDV is not present in Australia, so the conditions for the emergence of alomae disease do not exist as yet. Alomae disease kills taro plants and can completely destroy taro crops (Gollifer et al. 1978; Shaw et al. 1979). Cultivation of some taro cultivars ceased in the Solomon Islands as a result of alomae disease (Gollifer et al. 1978). Native populations of taro in the Northern Territory may be susceptible to TaRV and might decline if the virus becomes established and is spread. TaRV has not been recorded in other plant species. TaRV may infect other native Araceae, but no information is available.



Indirect


Impact score: D – significant at the district level If CBDV became established in Australia, and if the establishment of TaRV produced local outbreaks of alomae disease, then eradication or control would probably be attempted that would involve culling and quarantine. Many cultivars are likely to be susceptible to alomae disease, although some are resistant (Gollifer et al. 1978); commercial growers may be forced to change cultivar in response to an outbreak. Naturalised and native populations of taro may become reservoirs of the virus throughout the endangered area.

Domestic trade Impact score: B – minor significance at the local level If local outbreaks of alomae disease occurred trade in taro corms would be restricted.

International trade

Impact score: B – minor significance at the local level The taro export trade from Australia is small. However, presence of TaRV in Australia would lead to prohibition of exports to countries free of TaRV, if it was shown to be involved in alomae disease.


Impact score: A – indiscernible at the local level Reoviruses replicate in their insect vectors, but no effects have been reported that indicate disease (Fauquet et al. 2005). No information was found indicating possible effects on the environment.


The unrestricted risk for taro reovirus is: VERY LOW.


The unrestricted risk estimate for taro reovirus of ‘very low’ achieves Australia’s ALOP. Therefore, specific risk management measures are not required for this pest.

Review of import conditions for fresh taro corms Pest risk assessment – Taro vein chlorosis virus

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4.21 Taro vein chlorosis Taro vein chlorosis virus (TaVCV) TaVCV is a nucleorhabdovirus that has only been detected in taro from the Philippines and some Pacific Island countries. Infected plants are affected by vein chlorosis that spreads between the veins and may progress to vein necrosis, and their leaves may droop at the edges or become tattered (Revill et al. 2005b; Carmichael et al. 2008). TaVCV has not been detected in a latent infection (Pearson et al. 1999; Revill et al. 2005a). Usually 3–4 leaves are affected and the plants recover with subsequent leaves appearing healthy (Carmichael et al. 2008). It is not known how the virus is transmitted, but other nucleorhabdoviruses are transmitted by aphids (Aphididae), leafhoppers (Cicadellidae) or planthoppers (Delphacidae) (Jackson et al. 2005). The planthopper Tarophagus prosperina is suspected to be a vector (QUT 2003), although no evidence has been reported.

It has been proposed that TaVCV is involved in alomae disease (Carmichael et al. 2008). TaVCV has been found in some plants with alomae disease, but data from two surveys does not support the proposed association with the disease (Pearson et al. 1999; Revill et al. 2005a). CBDV, TaBV and TaRV are also found in plants with the disease (James et al. 1973; Shaw et al. 1979; Revill et al. 2005a) and it seems possible that a combination of two of these viruses causes alomae disease. Plants with alomae disease are stunted and malformed; they develop chlorosis and/or progressive necrosis. Some collapse, and all finally rot and die (Cook 1978; QUT 2003).

Tests of taro grown in Pacific Island countries have identified TaVCV in taro from the Federated States of Micronesia, Fiji, New Caledonia, Papua New Guinea, the Philippines, the Solomon Islands and Vanuatu (Pearson et al. 1999; Revill et al. 2005b; Davis et al. 2005; Davis et al. 2006). It may also be present in the Republic of Palau and Tuvalu (Pearson et al. 1999).



The likelihood that Taro vein chlorosis virus will arrive in Australia with the importation of fresh taro corms from any country where this pest is present is: HIGH. • TaVCV is widespread in taro in some Pacific Island countries (Shaw et al. 1979; Revill et

al. 2005a; Carmichael et al. 2008). • TaVCV infects systemically and is likely to be present in some or all corms from infected

plants (Pearson et al. 1999; Revill et al. 2005b). • Taro plants infected by TaVCV develop vein chlorosis and some of them develop vein

necrosis (Revill et al. 2005a). • Usually 3–4 leaves are affected and the plants recover, with subsequent leaves appearing

healthy (Carmichael et al. 2008). • By analogy with other virus infections from which plants have recovered (Gibbs and

Harrison 1976; Carmichael et al. 2008), plants that have recovered from TaVCV may retain the virus.

• Growers do not normally attempt to control the spread of this virus as the plants recover from the symptoms (Carmichael et al. 2008).


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• Corms from infected plants are unlikely to be removed during the grading and packing process.

• The condition of corms from infected plants has not been reported. It is highly likely that some infected corms will be indistinguishable from uninfected corms, so corms carrying the virus are likely to escape detection.

• Taro corms infected with TaVCV could be imported.


The likelihood that Taro vein chlorosis virus will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country, is: HIGH. • Imported corms are intended for human consumption. Corms will be distributed to many

localities by wholesale and retail trade and by individual consumers. • If infected corms are imported, they are very likely to be distributed. • Consumers will carry small quantities of taro corms to urban, rural and natural localities.

Small amounts of corm waste could be discarded in these localities. • Some corms will be distributed to areas where taro or other aroid species grow. • Small amounts of corm waste could be discarded in domestic compost. • Discarded corm waste of infected small corm taro may sprout and develop into infected




The likelihood that Taro vein chlorosis virus will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country, is: HIGH.

4.21.2 Probability of establishment The likelihood that Taro vein chlorosis virus will establish within Australia, based on a comparison of factors in the source and destination areas considered pertinent to its survival and reproduction, is: MODERATE. • TaVCV has established in a number of Pacific Island countries. • If a volunteer taro plant grows from a corm carrying TaVCV, the plant may be infected

with the virus. • Small corm taro will sprout readily from lateral buds in the corm, and so may be

propagated easily. Large corm taro is more difficult to propagate. New plants are likely to be infected with the virus.



• Colocasia esculenta was included in a list of the 200 most invasive plants in South East Queensland by Batianoff and Butler (2002). Hicks and Nguyen (2004) cautioned about


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disposal of waste corms of the eddoe (var. antiquorum) type, noting that the plants have the potential to become an invasive weed species.

4.21.3 Probability of spread The likelihood that Taro vein chlorosis virus will spread within Australia, based on a comparison of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of the pest, is: HIGH. • TaVCV is a nucleorhabdovirus (Revill et al. 2005b). It is not known how the virus is

transmitted, but other nucleorhabdoviruses are transmitted by aphids (Aphididae), leafhoppers (Cicadellidae) or planthoppers (Delphacidae) (Jackson et al. 2005).

• The planthopper Tarophagus prosperina and related planthoppers are suspected to be vectors (QUT 2003), although no evidence has been reported.

• The planthoppers Tarophagus persephone and Tarophagus colocasiae, which are close relatives of Tarophagus proserpina, occur in Queensland and the Northern Territory on wild taro (Matthews 2003; AICN 2011; CABI 2011).

• TaVCV may spread if a vector insect feeds on an infected volunteer plant and then transmits the virus to healthy taro plants.

• Infected plants are affected by vein chlorosis that spreads between the veins and may progress to vein necrosis. Their leaves may droop at the edges or become tattered (Revill et al. 2005b; Carmichael et al. 2008).

• Symptoms induced by TaVCV may be confused with those produced by DsMV and TaBV, both of which occur in Australia (Carmichael et al. 2008).

• The application of insecticides may reduce the spread of the virus by insects. • If the virus is detected in a crop, destruction of the taro plant is likely to prevent the virus

from spreading, as long as no vector is present (Carmichael et al. 2008). • TaVCV may spread to naturalised and native populations of taro.

4.21.4 Probability of entry, establishment and spread The likelihood that Taro vein chlorosis virus will be imported as a result of trade in fresh taro corms from any country where this pathogen is present, be distributed in a viable state to a susceptible host, establish and spread within Australia, is: MODERATE.

4.21.5 Consequences Assessment of the potential consequences (direct and indirect) of Taro vein chlorosis virus is: LOW.


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Direct


Impact score: D – significant at the district level TaVCV is probably spread by certain planthopper, leafhopper or aphid species. Planthoppers that could spread the virus are present in Queensland and the Northern Territory (Matthews 2003; QUT2003), and these territories could be affected if an incursion occurred. Infected plants are affected by vein chlorosis that spreads between the veins and may progress to vein necrosis; their leaves may droop at the edges or become tattered (Revill et al. 2005b; Carmichael et al. 2008). Corm production is likely to be reduced, but no measurements of losses have been made (Carmichael et al. 2008). Native populations of taro in the Northern Territory may be susceptible to TaVCV and might decline if the virus becomes established and spreads. TaVCV has not been recorded in other plant species. It is not known if the virus may infect other plant species.



Indirect


Impact score: C – minor significance at the district level Corm production is likely to be reduced, but no measurements of losses have been made (Carmichael et al. 2008). If TaVCV becomes established in Australia, eradication or control measures may be initiated. Measures might involve culling and quarantine, growing resistant cultivars, and spraying with insecticides. Naturalised and native populations of taro may become reservoirs of the virus.

Domestic trade Impact score: B – minor significance at the local level If TaVCV becomes established in Australia it may result in interstate trade restrictions on taro, as well as potential loss of markets and some industry adjustment.

International trade

Impact score: B – minor significance at the local level The taro export trade from Australia is small. Restrictions are possible for exports of taro to countries that do not have TaVCV.


Impact score: A – indiscernible at the local level No information was found indicating possible effects on the environment.


The unrestricted risk for Taro vein chlorosis virus is: LOW.


The unrestricted risk estimate for Taro vein chlorosis virus of ‘low’ exceeds Australia’s ALOP, and specific risk management measures are required for this pest.

Review of import conditions for fresh taro corms Pest risk assessment– Tomato zonate spot virus

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4.22 Tomato zonate spot tomato zonate spot virus (TZSV) TZSV is the proposed name for a recently described virus belonging to the Tospovirus genus (Dong et al. 2008). It was first observed on tomato (Lycopersicum esculentum) and chilli (Capsicum annuum) plants in Yunnan, China. Subsequent field surveys found taro plants with leaves displaying TZSV-like symptoms, which reacted positively to TZSV-specific antiserum. Other plants suspected of TZSV infection include carnation (Dianthus caryophyllus), curly dock (Rumex crispus) and spinach (Spinacia oleracea) (Dong et al. 2008).

Diseased plants exhibit concentric zoned ringspots on tomato and chilli fruits and necrotic lesions on the leaves. The disease was reported to have a devastating effect on the affected crops (Dong et al. 2008). The means of virus transmission has not been confirmed, although thrips are known vectors of tospoviruses (Persley et al. 2007), the most important of which is Frankliniella occidentalis, the Western flower thrips (Moritz et al. 2004). Three thrips species (Frankliniella occidentalis, Thrips palmi and Thrips tabaci) were found in fields with diseased plants in China (Dong et al. 2008). Tospoviruses are not transmitted by other sap-sucking insects such as aphids and leafhoppers, or by chewing insects such as beetles. They do not spread in seed or on equipment used for cutting, pruning and cultivation. These viruses do not survive in soil or decaying crop residues (Persley et al. 2007). Tospoviruses can be spread in infected plant parts used for plant propagation such as cuttings and bulbs (Persley et al. 2007).

Tospoviruses are transmitted to plants via the saliva of adult thrips that acquired these pathogens from infected plants as first or early second instar larvae (Moritz et al. 2004). The larvae do not transmit the virus until after pupation, as the virus needs time to multiply and move to the salivary glands (Persley et al. 2007). During the early larval stages, there is a temporary proximal association between the mid-gut, visceral muscles and salivary glands, where the cells fuse. The virus can move from the mid-gut and muscles to the salivary glands during this early stage of development. During the second instar stage, these organs become spatially separated, and further movement of the virus into the salivary glands is prevented (Moritz et al. 2004). While adult thrips may acquire the virus, they cannot transmit it to new hosts (Persley et al. 2007; Whitfield et al. 2005). In adult thrips, the virus accumulates and replicates in the malpighian tubules, allowing for a possible second mode of transmission via excrement (Moritz et al. 2004), although this has not been demonstrated.

At this time, TZSV has only been reported from Yunnan Province in China (Dong et al. 2008), although it may be present elsewhere but not yet identified.



The likelihood that tomato zonate spot virus will arrive in Australia with the importation of fresh taro corms from any country where this pest is present is: MODERATE. • TZSV is only known to be present in the Yunnan Province of China (Dong et al. 2008). • Taro is grown in this region, and infected taro plants have been reported.


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• TZSV probably infects systemically and is likely to be present in some, or all, corms from infected plants. It is not known whether infected plants would produce marketable corms.

• Symptoms on corms have not been reported and it is possible that infected corms may be imported undetected. Tospoviruses spread via infected material used for propagation (Persley et al. 2007).

• Taro corms infected with TZSV could be imported.


The likelihood that tomato zonate spot virus will be distributed within Australia in a viable state to a susceptible part of a host, as a result of the processing, sale or disposal of fresh taro corms from any country, is: HIGH. • Imported corms are intended for human consumption. Corms will be distributed to many

localities by wholesale and retail trade and by individual consumers. • Consumers will carry small quantities of taro corms to urban, rural and natural localities.

Small amounts of corm waste could be discarded in these localities. • Some corms will be distributed to areas where taro or other host plants, including tomato,

chilli, carnation and spinach, are growing. Susceptible host plants are widely distributed and common in many parts of Australia.

• Small amounts of corm waste could be discarded in domestic compost. • Discarded corm waste of infected small corm taro may sprout and develop into infected

plants. • Some small corm taro may be planted for domestic cultivation instead of being consumed.


The likelihood that tomato zonate spot virus will enter Australia and be distributed in a viable state to a susceptible host, as a result of trade in fresh taro corms from any country, is: MODERATE.

4.22.2 Probability of establishment The likelihood that tomato zonate spot virus will establish within Australia, based on a comparison of factors in the source and destination areas considered pertinent to its survival and reproduction, is: HIGH. • Establishment of TZSV outside Yunnan Province, China has not been reported. • If a volunteer taro plant grows from a corm carrying TZSV, the plant may be infected with

the virus. • Tospoviruses can establish via infected corms used for propagation (Persley et al. 2007). • Small corm taro will sprout readily from lateral buds in the corm, and so may be

propagated easily (Onewueme 1999). Large corm taro is more difficult to propagate. New plants are likely to be infected with the virus.




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• Other hosts such as tomato, chilli, carnation and spinach are commonly grown in Australian gardens, providing numerous potential host plants.

4.22.3 Probability of spread The likelihood that tomato zonate spot virus will spread within Australia, based on a comparative assessment of those factors in the source and destination areas considered pertinent to the expansion of the geographic distribution of the pest, is: HIGH. • TZSV is a tospovirus (Dong et al. 2008). Other tospoviruses such as Tomato spotted wilt

virus (TSWV) and Impatiens necrotic spot virus (INSV) have spread widely in Europe and the Americas. TSWV is one of the most widespread and damaging plant viruses in Australia (Persley et al. 2007).

• Plant-infecting tospoviruses are transmitted by thrips (Thripidae) (Persley et al. 2007). While the specific thrips vectors of TZSV are not known, Frankliniella occidentalis, Thrips palmi and Thrips tabaci were recorded in the fields where the virus was detected (Dong et al. 2008). These thrips species are all found in Australia (AICN 2011; Persley et al. 2007), and are known vectors of a number of other tospoviruses (Whitfield et al. 2005).

• TZSV may spread if an immature thrips feeds on an infected volunteer plant and then later feeds on healthy taro plants.

• Insecticides would only have limited effectiveness for stopping the spread of the virus by thrips.

• TZSV may spread to naturalised and native populations of taro and other hosts such as carnation, chilli, spinach and tomato.


The overall likelihood that tomato zonate spot virus will be imported as a result of trade in fresh taro corms from any country where this pathogen is present, be distributed in a viable state to a susceptible host, establish and spread within Australia, is: MODERATE.

4.22.5 Consequences Assessment of the potential consequences (direct and indirect) of tomato zonate spot virus is: LOW.


Direct


Impact score: D – significant at the district level Thrips that might spread TZSV are present in all Australian states, so plant health could be affected if an incursion occurred. TZSV has a wide host range that includes both agricultural crops and ornamental plant species. As well as taro, TZSV is known to affect tomato, chilli, carnations and spinach, while a number of other species have been found susceptible in inoculation tests (Dong et al. 2008).




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Indirect


Impact score: D – significant at the district level If TZSV became established in Australia, it is unlikely that eradication would be possible. The thrips that are suspected of vectoring the virus are common and widespread in Australia. While pest management in commercial crops may reduce infection locally, naturalised and native populations of taro or other hosts may become reservoirs of the virus throughout the endangered area. It is not known if host plants have varieties that are more resistant to TZSV infection.

Domestic trade Impact score: D – significant at the district level The effect of TZSV infection on taro corms is not known, although the disease is reported to be devastating to tomatoes and chillies (Dong et al. 2008). The taro leaves develop necrotic lesions, which may adversely affect corm quality. More severe economic impacts would be expected in other crops like tomato and chilli, where ringspots on the fruit are likely to render them unmarketable. Trade in taro corms may be restricted to prevent spread of the virus.

International trade

Impact score: C – minor significance at the district level The taro export trade from Australia is small. However, the presence of TZSV in Australia may lead to prohibition of taro exports to countries free of TZSV. As well as potential yield losses, other crops may also be negatively affected by export restrictions, although commodities such as tomatoes and chillies are unlikely to spread the virus via trade. Tospoviruses are not spread via seed (Persley et al. 2007).


Impact score: A – indiscernible at the local level No information was found indicating possible effects on the environment.


The unrestricted risk for tomato zonate spot virus is: LOW.


The unrestricted risk estimate for tomato zonate spot virus of ‘low’ exceeds Australia’s ALOP, and specific risk management measures are required for this pest.

Review of import conditions for fresh taro corms Pest risk assessment conclusion

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4.23 Pest risk assessment conclusion The unrestricted risk posed by Tarophagus proserpina, Phytophthora colocasiae, colocasia bobone disease virus, the French Polynesian strain of Dasheen mosaic virus, Taro vein chlorosis virus and tomato zonate spot virus are estimated to exceed Australia’s ALOP. Therefore, additional risk management measures for these pests are required to reduce the risks to a level consistent with Australia’s ALOP.

The unrestricted risk of the other pests assessed achieves Australia’s ALOP and therefore risk management measures are not required.

The results of these risk estimates are summarised in Table 4.2. The rationale for each value of the pest risk assessment, summarised in this table, is described in the relevant sections above.

The proposed pest risk management measures are discussed in Section 5.

Key to table 4.2

Likelihoods for entry, establishment and spread

N negligible EL extremely low VL very low L low M moderate H high P[EES] overall probability of entry, establishment and spread

Assessment of consequences from pest entry, establishment and spread

PLH plant life or health OE other aspects of the environment EC eradication control etc. DT domestic trade IT international trade ENC environmental and non-commercial A-G consequence impact scores are detailed in section 2.2.3 URE unrestricted risk estimate. This is expressed on an ascending scale from negligible to extreme


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Table 4.2: Summary of risk assessments for quarantine pests for fresh taro from all countries where pests are present

Pest name

Likelihood of Consequences

URE Entry Establishment Spread P[EES]

Importation Distribution Overall Direct Indirect Overall PLH OE EC DT IT ENC

Weevils [Coleoptera: Curculionidae]

Elytroteinus subtruncatus L M L L M VL C A B B B A VL N

Beetles [Coleoptera: Scarabaeidae]

Eucopidocaulus tridentipes

L L VL M H VL E A D C B A M VL

Papuana biroi

Papuana cheesmanae

Papuana huebneri

Papuana inermis

Papuana japenensis

Papuana laevipennis

Papuana semistriata

Papuana szentivanyi

Papuana trinodosa

Papuana uninodis

Planthoppers [Hemiptera: Delphacidae]

Tarophagus proserpina H H H H M M D A B B B A L L

Armoured scales [Hemiptera: Diaspididae]

Aspidiella hartii VL M VL M H VL D A B B B A L N

Mealybugs [Hemiptera: Pseudococcidae]

Paraputo aracearum M M L M H L D A B B B A L VL

Paraputo leveri


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Pest name




Aphids [Hemiptera: Pemphigidae]

Patchiella reaumuri L L VL M M VL E A C B B A M VL

Nematodes

Helicotylenchus microcephalus L M L H H L D A C B B A L VL

Helicotylenchus mucronatus

Hirschmanniella miticausa M L L H M L D A D B B A L VL

Longidorus sylphus VL L VL M M VL D A C B B A L N

Bacteria

Xanthomonas axonopodis pv. dieffenbachiae M M L M H L D A C B B C L VL

Fungi

Corallomycetella repens VL M VL M M VL C A B B B A VL N

Rosellinia pepo L M L M M L D A B B B A L VL

Straminopila

Phytophthora colocasiae H M M H H M E A D B B B M M

Phytophthora sp. (Taro pocket rot) M M L L M VL D A C B B A L N

Pythium carolinianum M M L M H L D B C B B B L VL

Viruses

colocasia bobone disease virus (CBDV) H H H M H M D A D B B A L L

French Polynesian strain of Dasheen mosaic virus (FP-DsMV) M H M H H M D C C B B A L L

taro reovirus (TaRV) M H M M M L D A D B B A L VL


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Pest name




Taro vein chlorosis virus (TaVCV) H H H M H M D A C B B A L L

tomato zonate spot virus (TZSV) M H M H H M D A D D C A L L

Note: The recently reported pathogen Marasmiellus colocasiae has been excluded from the assessment due to insufficient available information.

Review of import conditions for fresh taro corms Pest risk management

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5 Pest risk management

This chapter provides information on the management of quarantine pests identified with an unrestricted risk exceeding Australia’s appropriate level of protection (ALOP). In estimating the unrestricted risk, existing commercial production practices and minimum border procedures in Australia were taken into consideration. The proposed phytosanitary measures are described below.

5.1 Pest risk management measures and phytosanitary procedures Specific pest risk management measures, including an operational system, are proposed for fresh taro corms from all countries, excluding those countries where the recently reported fungal pathogen Marasmiellus colocasiae occurs, to reduce the restricted risk to a level that achieves Australia’s ALOP.

This pest risk analysis has been conducted on corms of both the large and small corm varieties of taro. Corms of large corm taro are traditionally marketed with a short tuft of petiole bases attached to protect the apical bud and ensure the corms stay physiologically active, which delays the development of storage rots. Corms of small corm taro are cormels (daughter corms) that do not have petiole bases attached at the apical end.

The importation of small corm taro (Colocasia esculenta var. antiquorum) remains prohibited until further notice. However, countries that are able to demonstrate freedom from taro leaf blight, colocasia bobone disease virus, the French Polynesian strain of Dasheen mosaic virus, Taro vein chlorosis virus and tomato zonate spot virus may apply for access for small corm taro. Applications will be assessed on a case-by-case basis. In such a case, appropriate import conditions will be determined at a later date.

The specific pest risk management measures proposed for fresh taro corms are summarised in Table 5.1.

Table 5.1: Phytosanitary measures proposed for quarantine pests of fresh taro corms

Pest Common name Measures Arthropods

Tarophagus proserpina taro planthopper Inspection and remedial action for taro from countries where present

Topping of corms of large corm taro from countries where present

Straminopila

Phytophthora colocasiae taro leaf blight Area (country) freedom from taro leaf blight

Viruses

colocasia bobone disease virus colocasia bobone disease

Topping of corms of large corm taro from countries where present

Prohibition of corms of small corm taro from countries where present French Polynesian strain of Dasheen

mosaic virus dasheen mosaic

Taro vein chlorosis virus taro vein chlorosis

tomato zonate spot virus tomato zonate spot


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5.1.1 Management for taro planthopper

Tarophagus proserpina has been assessed to have an unrestricted risk estimate of ‘low’ for taro corms imported from countries hosting this pest, and additional measures are therefore required to manage this risk.

The major risks from Tarophagus proserpina are eggs laid in the petioles or petiole bases on the corm, or nymphs or adults hiding in the petioles. Taro planthoppers are known to establish via planting materials. Corms of the large corm variety with petiole bases that could potentially be used for growing purposes present a significant risk.

The proposed risk management measures are: • inspection to ensure that taro corms infested with nymphs and adults of Tarophagus

proserpina are identified and subjected to appropriate remedial action • topping of corms of large corm taro to remove the petiole bases that may carry eggs,

nymphs and adults of Tarophagus proserpina.

All petiole material and growing points of the corm must be removed. Topping of large taro corms may take place either in the country of origin, or on arrival, before phytosanitary inspection of the corms.

The objective of these measures is to reduce the likelihood of importation for Tarophagus proserpina to at least ‘low’. The restricted risk would then be reduced to ‘very low’, which would achieve Australia’s ALOP.

5.1.2 Management for taro leaf blight

Phytophthora colocasiae has been assessed to have an unrestricted risk estimate of ‘moderate’ for taro corms imported from countries hosting this pathogen, and additional measures are therefore required to manage this risk.

The major risk from Phytophthora colocasiae is the importation of corms bearing viable sporangia or zoospores (particularly between petiole bases) that are subsequently diverted from their intended use for human consumption and used as planting material. Infected and rotting corms bearing viable hyphae or spores could also be discarded near susceptible hosts.

The potential for unregulated movement of planting materials and the natural ability of Phytophthora colocasiae pathogen to spread means that country freedom is required.

The proposed risk management measure for countries where this pathogen is present is: • Country freedom from Phytophthora colocasiae. Taro corms must only be sourced from

countries declared free of taro leaf blight.

The objective of this measure is to reduce the likelihood of importation for Phytophthora colocasiae to at least ‘very low’. The restricted risk would then be reduced to ‘very low’, which would achieve Australia’s ALOP.

Alternative measures for taro leaf blight proposed by exporting countries, e.g. systems approach, pest free place of production etc., may be considered on a case-by-case basis in the future. Any potential imports subject to alternative measures would be governed by separate import conditions.


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5.1.3 Management for colocasia bobone disease, French Polynesian strain of dasheen mosaic, taro vein chlorosis and tomato zonate spot

Colocasia bobone disease virus, the French Polynesian strain of Dasheen mosaic virus, Taro vein chlorosis virus and tomato zonate spot virus have been assessed to have unrestricted risk estimates of ‘low’ for taro corms imported from countries hosting these pathogens, and additional measures are therefore required to manage these risks.

The major risks from these viruses are from the import of infected corms, their diversion from their intended use of human consumption to planting material, sprouting of the corms, and transmission of the viruses to other plants by their insect vectors.

The proposed risk management measures for taro from countries where these viruses are present are: • topping of corms of large corm taro to remove the petiole bases and the apical growing

points to reduce the likelihood that infected plants establish, either from discarded corm waste or corms that are used for propagation

• prohibition of corms of small corm taro, which could grow into infected plants due to their ease of propagation.

All petiole material and growing points of the corm must be removed, and the corm must be free of lateral shoots, suckers and daughter corms. Topping of large taro corms may take place either in the country of origin, or on arrival, before phytosanitary inspection of the corms.

The objective of these measures is to reduce the likelihood of establishment for colocasia bobone disease virus, the French Polynesian strain of Dasheen mosaic virus, Taro vein chlorosis virus and tomato zonate spot virus to at least ‘low’. The restricted risk would then be reduced to ‘very low’, which would achieve Australia’s ALOP.

5.1.4 Operational system for the maintenance and verification of phytosanitary status

A system of operational procedures is necessary to maintain and verify the phytosanitary status of imported fresh taro corms. This is to ensure that the proposed risk management measures have been met and are maintained. The components of the proposed operational system are described below.

Phytosanitary certification by a NPPO, or other relevant agency nominated by the NPPO The objectives of phytosanitary certification are to ensure that:

• an International Phytosanitary Certificate (IPC) is issued for each consignment, consistent with ISPM 12 Guidelines for Phytosanitary Certificates (FAO 2001b), to provide formal documentation to AQIS verifying the relevant measures have been undertaken offshore

• each IPC includes a description of the consignment (including the taro variety and country of origin).


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Additional Phytosanitary Certificate declarations

Each consignment must be accompanied by an original IPC endorsed with the following additional declarations:

1. The taro in this consignment is Colocasia esculenta var. esculenta and not Colocasia esculenta var. antiquorum

AND 2. The tubers are sourced from [name of country], which is free of taro leaf blight

(Phytophthora colocasiae)

AND 3 a). The tubers have been inspected and found to be topped and free from all foliage

including petiole bases, and free from sprouts, suckers and attached daughter corms

OR b). The taro in this consignment was sourced from [name of country], which is free of taro planthopper (Tarophagus proserpina), colocasia bobone disease virus, French Polynesian strain of Dasheen mosaic virus, Taro vein chlorosis virus and tomato zonate spot virus.

If countries propose alternative measures for managing taro leaf blight, or apply for access for small corm taro and can demonstrate that identified quarantine risks can be satisfactorily mitigated, then in the event that access is granted, alternative Phytosanitary Certificate declaration requirements will apply.

Packaging and labelling

The objectives of the requirement for packaging and labelling are to ensure that:

• fresh taro exported to Australia is not contaminated by quarantine pests or regulated articles (e.g. trash, soil and weed seeds)

• unprocessed packing material (which may vector pests not identified as being on the pathway) is not imported with the taro corms

• all wood used in the packing of the commodity complies with AQIS conditions (see AQIS publication ‘Cargo containers: Quarantine aspects and procedures’).

On-arrival phytosanitary inspection and clearance by AQIS The objectives of this procedure are to ensure that:

• on arrival in Australia, each consignment as defined by a single phytosanitary certificate is inspected by AQIS at the first port of entry for quarantine pests and regulated articles

• inspection lots are inspected using the standard AQIS inspection protocol, which includes optical enhancement where necessary

• a sample size for taro corms of 600 units (a unit is a single taro corm) is inspected from each consignment. If a consignment has less than 1000 units, then 450 units are to be inspected. For consignments of less than 450 units, all units must be inspected


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• if no live quarantine pests or other regulated articles are detected in the inspection lot, the consignment will be released from quarantine

• inspection lots will fail if quarantine pests and/or regulated articles are detected by AQIS during on-arrival inspections. Remedial action is to be taken when this occurs

• if the product continually fails inspection, the export program may be suspended and audited by AQIS, with reinstatement after AQIS is satisfied that appropriate corrective action has been taken.

Policy on unidentified disease symptoms

Australia has a long standing policy of requiring treatment for diseased material where identification of the pathogens responsible is not possible. Where diseased taro corms are detected and identification of the pathogens is not possible, or cannot be provided within a practical time, then the product is deemed to pose a disease risk to Australia and remedial action is required.

Remedial action for non-compliance – on-arrival verification The objectives of the proposed requirements for remedial action(s) for non-compliance during on-arrival verification are to ensure that any quarantine risk is addressed by remedial action, as appropriate, for consignments that do not comply with import requirements.

5.2 Review of policy Australia collects data on pests intercepted in trade and uses this information to validate import policy. Depending on the level and type of pest interceptions at the border, Biosecurity Australia may consider further revisions of this policy and the operational requirements.

Review of import conditions for fresh taro corms Conclusion

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6 Conclusion

This review of import conditions supports the continuation of existing import conditions for fresh large corm taro, with an additional condition to mitigate the risks posed by Phytophthora colocasiae. The report recommends a conditional relaxation of the prohibition on importation of small corm taro (Colocasia esculenta var. antiquorum), adopted as an emergency measure in 2006. Countries that are able to demonstrate freedom from taro leaf blight, colocasia bobone disease virus, the French Polynesian strain of Dasheen mosaic virus, Taro vein chlorosis virus and tomato zonate spot virus may apply for access for small corm taro. This will be assessed on a case-by-case basis at a later date. If it is determined that identified quarantine risks can be mitigated, then alternative draft import conditions will be developed. A new pathogen, Marasmiellus colocasiae, recently reported from Brazil was not assessed in the draft report, and is considered to be outside the scope of this report.

The findings of this report are based on a comprehensive analysis of relevant scientific literature. Biosecurity Australia considers that the risk management measures proposed in this report will provide an appropriate level of protection against the pests identified in this risk analysis. Various risk management measures may be suitable to manage the risks associated with fresh taro from all countries. Biosecurity Australia will consider any other measures suggested by stakeholders that provide an equivalent level of phytosanitary protection.

Review of import conditions for fresh taro corms Appendices

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Appendices

Review of import conditions for fresh taro corms Appendix A

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Appendix A: Initiation and pest categorisation for pests of taro

Initiation (columns 1 – 2) identifies the pests of taro that have the potential to be on fresh corms produced using commercial production and packing procedures. Pest categorisation (columns 3 - 6) identifies which of the pests with the potential to be on taro corms are quarantine pests for Australia and require pest risk assessment. The steps in the initiation and categorisation processes are considered sequentially, with the assessment terminating at the first ‘No’ for columns 2, 4 or 5 or ‘Yes’ for column 3. Details of the method used in this IRA are given in Section 2: Method for pest risk analysis. Contaminating pests are not considered under categorisation. Contaminant pests are addressed under existing AQIS standard operational procedures.

Pest Potential to be on taro corms Present within Australia

Potential for establishment and spread Potential for economic consequences

Pest risk assessment required

ARTHROPODA: Arachnida: Acari

Acariformes (mites)

Rhizoglyphus minutus Manson, 1972 [Acaridae] Taro mite

Yes – Frequently intercepted in Australia and New Zealand on taro corms from the Pacific (Zhang 2003, 2004).

No record found. However, the taxonomy of Rhizoglyphus in Australia is confused due to a lack of detailed taxonomic study (Fan and Zhang 2003).

Yes – At least three other Rhizoglyphus species are found in Australia (Fan and Zhang 2003). The main host is taro, which is found in parts of Australia. Other hosts include yam and coconut (Zhang 2003), which are present in Australia. Taro has been imported for many years and there have been many mite interceptions. However, there are no records of establishment in Australia.

No – Rhizoglyphus minutus affects root crops such as taro and yams after harvest. It is most often associated with damaged tissue and with fungal attack (Trade Forum 2002). Fiji does not consider the mite to be a pest as such, because it does not damage the corm (Vinning 2003). It is not listed as one of the Rhizoglyphus species known to be agricultural pests in Diaz et al. (2000).

No

Tetranychus cinnabarinus (Boisduval, 1867) [Tetranychidae] Carmine spider mite

No – Adults and nymphs feed primarily on the undersides of the leaves. The mites tend to feed in ‘pockets’ often near the midrib and veins (Mau et al. 2007). Leaf trimming during harvest should exclude this pest from the pathway.

Yes (Halliday 2000). No

Tetranychus lambi Pritchard & Baker, 1955 [Tetranychidae] Banana spider mite

No – Feeds on leaves and fruit of host plants (Gutierrez and Schicha 1983). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Has been recorded in NSW and Qld (AICN 2011).

No


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Tetranychus marianae McGregor, 1950 [Tetranychidae] Spider mite

No – Colonies are found on the underside of leaves (Ochoa et al. 1994). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Has been recorded in Qld (AICN 2011).

No

MOLLUSCA: Gastropoda

Achatina fulica Bowditch, 1822 [Syn.: Lissachatina fulica (Bowditch, 1822)] [Achatinidae] Giant African snail

No – Giant African snail is a polyphagous feeder that is reported to eat taro plants, but only when pest populations are high. It is principally a foliar feeder, but will eat any live or dead plant tissue (Carmichael et al. 2008). Eggs are laid in the soil, so the main risk is hitchhiking juveniles or adults. Removal of leaves and soil will remove this pest from the pathway.

No record found. No

Pomacea canaliculata (Lamarck, 1822) [Ampullariidae] Golden apple snail

No – Voracious consumers of plant material. Egg masses are laid on any available surface, in wet conditions. These would normally be removed by cleaning methods employed to remove soil and surface contaminants in packing houses, and detected during routine entry inspection for contaminants. Removal of leaves and soil will remove this pest from the pathway.

No record found. No

ARTHROPODA: Insecta

Coleoptera (beetles)

Adoretus sinicus Burmeister, 1855 [Scarabaeidae] Chinese rose beetle

No – Adults feed on leaves at night, and larvae feed on rotting material in the soil and rarely attack living roots (Hawaii Department of Agriculture 2009). Reported eating taro leaves in Micronesia (Nafus 1997). Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No


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Adoretus versutus Harold, 1869 [Syn.: Adoretus vestitus Boheman, 1858; Adoretus vitiensis Nonfried, 1891; Adoretus insularis Fairmaire, 1897] [Scarabaeidae] Rose beetle

No – Adult beetles feed on leaves at night and shelter in the soil or under leaf litter during the day. The larvae feed on rotting material in the soil. They may attack living roots, but damage is only slight (Ecoport 2011). Leaf trimming during harvest and removal of soil and roots should exclude this pest from the pathway.

No record found. No

Apirocalus ebrius Faust, 1892 [Anthribidae] Horned weevil

No – Herbivorous leaf-feeding weevil (Smith 1978). Adult weevils attack soft growing points and leaves of taro and a range of other crops. Damage is often not serious (French 2006). Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Apirocalus terrestris Thompson, 1977 [Anthribidae] Horned weevil

No – Adult weevils attack soft growing points and leaves of taro and a range of other crops. Damage is often not serious (French 2006). Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Araecerus fasciculatus (De Geer, 1775) [Syn.: Araecerus coffeae (Fabricius, 1801)] [Anthribidae] Cocoa weevil

Yes – This weevil has been reported as a storage pest in tuber products. Larvae tunnel through the corm (CABI 2011).

Yes. Has been recorded in NSW, Qld, Tas., Vic. and SA (Zimmerman 1994).

No

Caedius demeijerei Gebien, 1920 [Tenebrionidae]

No – Beetles have been reported damaging beans, taro and radish. Adults are found on the ground under beans (French 2006). Leaf trimming during harvest and cleaning of corms should exclude this pest from the pathway.

No record found. No

Dermolepida noxium Britton, 1957 [Scarabaeidae] Chafer beetle

No – Leaf feeder on banana, but has been reported damaging taro (French 2006). Should be eliminated by normal packing procedures.

No record found. No


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Elytroteinus subtruncatus (Fairmaîre, 1881) [Circulionoidea] Fiji ginger weevil

Yes – The larval stage burrows into the corm (Mau and Martin Kessing 1992a).

No record found. Yes – Host plants, including avocado, sugarcane, lemon and taro (Follett et al. 2007) are present in many parts of Australia, so some spread could be anticipated.

Yes – Host plants include economic crops. Feeding of the larvae results in wilting and loss of vigour. If feeding is extensive, the host may die (Mau and Martin Kessing 1992a).

Yes

Eucopidocaulus tridentipes (Arrow, 1911) [Syn.: Papuana tridentipes Arrow, 1911] [Scarabaeidae] Taro beetle

Yes – Adult beetles tunnel into corms, eventually destroying them. Larvae feed on rotting vegetation, sawdust etc. (Macfarlane 1987; Carmichael et al. 2008).

No record found. Yes – Potential hosts include ornamental and native aroids. However damage is readily apparent and should be discovered on packing/ import inspection.

Yes – This species of taro beetle is a serious pest of taro, burrowing into the corms and making smooth-sided, round tunnels (Adams 2006b).

Yes

Glyptoporopterus sharpi (Faust, 1898) [Circulionoidea] Weevil

No – Has been reported on taro (French 2006), but leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Henosepilachna guttatopustulata (Fabricius, 1775) [Syn.: Epilachna guttatopustulata (Fabricius, 1775); Coccinella guttatopustulata Fabricius, 1775] [Coccinellidae] Large leaf eating ladybird

No – Both larvae and adults feed on foliage (Li 1993). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Has been recorded in NSW, NT, Qld, Tas. and Vic. (Li 1993; AICN 2011).

No

Melanhyphus clypealis (Arrow, 1937) [Scarabaeidae] Beetle

No – Scarab beetles are occasionally reported on taro (French 2006). Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Oryctes rhinoceros (Linnaeus, 1758) [Syn.: Oryctes stentor Castelnau, 1840; Scarabaeus rhinoceros Linnaeus, 1758] [Scarabaeidae] Rhinoceros beetle

No – Larvae live in rotting logs, tree stumps, compost heaps, sawdust etc. Adult beetles burrow into the growing points of coconut and oil palms (CABI 2011). Only incidentally associated with taro, and not noted as a pest for that species.

No. Has previously been recorded in Qld (CABI 2011).

No

Papuana biroi Endrödi, 1969 [Scarabaeidae] Taro beetle



Yes – Burrows into corm forming large tunnels and cavities that eventually destroy product (Carmichael et al. 2008).

Yes


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Papuana cheesmanae Arrow, 1941 [Scarabaeidae] Taro beetle




Yes

Papuana huebneri Fairmaire, 1879 [Scarabaeidae] Taro beetle




Yes

Papuana inermis Prell, 1912 [Scarabaeidae] Taro beetle




Yes

Papuana japenensis Arrow, 1941 [Scarabaeidae] Taro beetle




Yes

Papuana laevipennis Arrow, 1911 [Syn.: Papuana woodlarkiana subsp. laevipennis (Arrow, 1911)] [Scarabaeidae] Taro beetle




Yes

Papuana semistriata Arrow, 1911 [Scarabaeidae] Taro beetle




Yes

Papuana szentivanyi Endrodi, 1971 [Scarabaeidae] Taro beetle




Yes


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Papuana trinodosa Prell, 1912 [Scarabaeidae] Taro beetle




Yes

Papuana uninodis Prell, 1912 [Scarabaeidae] Taro beetle




Yes

Papuana woodlarkiana Montrouzier, 1855 [Syn.: Papuana woodlarkiana subsp. woodlarkiana (Montrouzier, 1855)] [Scarabaeidae] Taro beetle


Yes. Has been recorded in Qld and WA (Brooks 1965).

No

Phraotes torvus Marshall, 1956 [Circulionoidae] Taro spiny weevil

Yes – Reported severely chewing taro petioles in Papua New Guinea (French 2006). Adults feed on petioles and leaves (Maddison 1993).

No record found. No – Information on this species is scare. Possibly restricted to New Guinea, and not known to be invasive. No quarantine reports of this species (Maddison and Crosby 2009).

No – Not considered to be a pest species (Maddison and Crosby 2009).

No

Propsephus hawaiiensis (Candèze, 1881) [Elateridae] Click beetle

Yes – Larvae feed on the roots of a number of plants including taro (Watt 1986). No information is available on likelihood of larvae burrowing into the corm, but Elateridae larvae typically feed on live roots and dead plant material (Watt 1986).

No record found. Yes – Feeds on dead plant material in the soil, and larvae may feed on live roots of a number of plant species (Watt 1986).

No – There are few reports of this species being a pest, but it may have a minor impact on the roots of banana and sugarcane and some vegetables. Not recorded as a pest in the Pacific Islands Pest Database.

No

Propsephus tongaensis (Candèze, 1878) [Elateridae] Click beetle

No – Larvae feed on the roots of a number of plants in the Pacific, but Watt (1986) did not report taro as a host. Could be present in soil attached to poorly cleaned corms. Unidentified Elateridae beetles have been occasionally intercepted on taro from Fiji and Vanuatu (AQIS interception data).

No record found. No


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Propsephus sp. [Elateridae] Click beetle

Yes – Larvae of an unidentified species of Propsephus were recorded feeding on the roots of a number of plants, including taro in Samoa and Fiji (Watt 1986). Unidentified Elateridae beetles have been occasionally intercepted on taro from Fiji and Vanuatu (AQIS interception data).

No record found. Yes – Feeds on dead plant material in the soil, and larvae may feed on live roots of a number of plant species (Watt 1986).

No – There are few reports of Propsephus beetles being economic pests. It may have a minor impact on the roots of banana and sugarcane and some vegetables. Not recorded as a pest in the Pacific Islands Pest Database.

No

Thompsoniella deplanatus (Boheman, 1859) [Syn.: Atactus deplanatus (Boheman, 1859)] [Circulionoidae] Weevil

No – Reported to chew holes in taro leaves in Pohnpei (Nafus 1997). Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Tribolium castaneum (Herbst, 1797) [Tenebrionidae] Red flour beetle

Yes – Eggs can be laid in stored products, where the emerging larvae feed (CABI 2011).

Yes. Has been recorded in ACT, NSW, NT, Qld, SA, Tas., Vic. and WA (AICN 2011).

No

Dermaptera (earwigs)

Chelisoches morio (Fabricius, 1775) [Chelisochidae] Black earwig

No – Commonly associated with flowers of taro. Also damages banana flowers. It is a predator of small insects (French 2006). Should be eliminated by normal packing procedures.

No record found. No

Hemiptera (aphids, leafhoppers, mealybugs, phyllids, scales, true bugs, whiteflies)

Agathyrna praecellens Stål,1861 [Syn.: Astacops flavicollis Walker, 1871] [Coreidae]

No – Arboreal species (Cassis and Gross 2002) unlikely to be found on taro corms or roots.

Yes. Found in NE coastal Queensland, and the Iron Range, NW Queensland (Cassis and Gross 2002).

No

Aleurodicus dispersus Russell, 1965 [Aleyrodidae] Spiralling whitefly

No – Larvae and adults feed on the sap from foliage (Martin Kessing and Mau 1993). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in Qld (AICN 2011).

No


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Aleurodicus destructor Mackie, 1912 [Syn.: Aleurodes albofloccosa Froggatt, 1918; Aleyrodicus destructor Mackie, 1912] [Aleyrodidae] Coconut whitefly

No – Larvae and adults feed on the sap from foliage (Martin and Gillespie 2009). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NSW, NT, Qld, Tas., Vic. and WA (AICN 2011).

No

Aleurothrixus antidesmae Takahashi, 1933 [Aleyrodidae] Whitefly

No – Aleurithrixus spp. are leaf sap feeders, both as adults and larvae (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Aleurotrachelus trachoides (Back, 1912) [Aleyrodidae] Whitefly

No – Aleurotrachelus spp. are leaf sap feeders, both as adults and larvae (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Aphis gossypii Glover, 1877 [Aphididae] Cotton aphid

No – Leaf feeding species. Aphids move to younger leaves, stems and flowers when populations are high (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NSW, NT, Qld, SA, Tas., Vic. and WA (AICN 2011).

No

Aspidiella hartii (Cockerell, 1895) [Syn.: Aspidiotus hartii Cockerell, 1895] [Diaspididae] Yam scale

Yes – Colocasia esculenta is a host. Associated with root and tuber crops in storage (Ben-Dov et al. 2011).

No. There are unconfirmed records of this species in the Northern Territory (NTDPIF 2001).

Yes. Some host plants are present in Australia (Ben-Dov et al. 2011; Williams and Watson 1988), although they are neither widespread nor common. First-stage larvae are active crawlers, and are capable of seeking out suitable hosts (Mau and Martin Kessing 1992b).

Yes. Hosts include some minor crop species including taro, sweet potato, turmeric, yam and ginger (Ben-Dov et al. 2011; Williams and Watson 1988).

Yes

Aspidiotus destructor Signoret, 1869 [Syn.: Aspidiotus cocotis Newstead, 1893; Aspidiotus lataniae Green, 1980] [Diaspididae] Coconut scale

No – This pest is usually found in densely massed colonies on the lower surfaces of leaves, except in extremely heavy infestations where it may be present on both sides. It may also be found on petioles, peduncles and fruits (Martin Kessing et al. 2007). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NT and Qld (AICN 2011).

No


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Astacops villicus (Stål,1867) [Lygaeidae]

No – Small bugs causing wilting of taro leaves (French 2006). Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Bemisia leakii (Peal, 1903) [Syn.: Aleurodes leakii Peal, 1903] [Aleyrodidae] Whitefly

No – Leaf sap suckers. Members of this group [Bemisia leakii, Bemisia afer and Bemisia hancocki] are not considered to be pests (Ecoport 2011), but they may transmit viruses. Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Bemisia tabaci (Gennadius, 1889) ‘strain B’ [Syn.: Bemisia argentifolii Bellows & Perring, 1994; Bemisia tabaci (Gennadius, 1889) (B biotype)] [Aleyrodidae] Silver leaf whitefly

No – Leaf sap suckers. Adults and juveniles (nymphs) feed by sucking the sap from the host plants (Ecoport 2011). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NT (APPD 2009), NSW, Qld and Tas. (CABI 2011). It has been intercepted in WA (CABI 2011).

No

Bemisia tabaci (Gennadius, 1889) 'Nauru strain' [Aleyrodidae] Sweet potato / tobacco / cotton whitefly

No – Leaf sap suckers that may transmit viruses (Ecoport 2011). Leaf trimming during harvest should exclude this pest from the pathway.

No record of this strain in Australia.

No

Brachylybas variegatus (Le Guillou, 1841) [Coreidae] Brown coreid bug

Yes – Reported on taro in Tonga (Ecoport 2011) and Fiji (Mitchell 2000). Coreids are large bugs with repellent odours, mainly feeding on leaves, shoots and fruits (Gross 1991). Listed by Mitchell (2000) as a minor pest, feeding on leaves and petioles of taro.

No record found. Yes – This species has limited distribution (Fiji and Tonga), but host plants are common in Australia.

No – This species has been reported on crop species such as tomatoes and cucurbits, but is only a minor pest (Mitchell 2000).

No

Coccus hesperidum Linnaeus, 1758 [Coccidae] Brown soft scale

No – Leaf feeding species (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in ACT, NSW, NT, Qld, SA, Tas., Vic. and WA (AICN 2011).

No


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Coccus longulus (Douglas, 1887) [Coccidae] Long shield scale

No – The long brown scale, like other soft scales, feeds from the phloem of the host plant and may be found on stems, leaves and green twigs where they are associated with veins (Copland and Ibrahim 1985). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NSW, NT, Qld and SA (AICN 2011).

No

Cyrtorhinus fulvus (Knight, 1935) [Miridae] Mirid

Yes – Predatory species that oviposits in the petioles of taro, usually in plants where taro planthoppers (Tarophagus colocasiae) have laid eggs (Wheeler 2001).

No record found. Yes – Predator of taro planthopper Tarophagus proserpina, which is present in parts of Australia.

No – Cyrtorhinus fulvus is not a plant pest. It is used as a biological control agent against the taro planthopper in parts of the Pacific. Although typically associated with young leaves and petioles, it may occasionally arrive with corms.

No

Diaspis bromeliae (Kerner, 1778) [Diaspididae] Pineapple scale

No – Found on the leaves, fruit and stems of hosts (Watson 2011). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NSW and Qld (AICN 2011).

No

Dysmicoccus brevipes (Cockerell, 1893) [Pseudococcidae] Pineapple mealybug

No – Infestations of Dysmicoccus brevipes occur on the foliage, stems and fruit of host plants, but is common on the roots of pineapple (CABI 2011).

Yes. Recorded in NSW, NT, Qld, Tas. and WA (AICN 2011).

No

Ferrisia virgata Cockerell, 1893 [Syn.: Ferrisiana virgata (Cockerell, 1893); Helicoccus malvastrus McDaniel, 1962] [Pseudococcidae] Striped mealybug

No – Infestations remain clustered around the terminal shoots, leaves and fruit of hosts, sucking the sap (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NT and Qld (AICN 2011).

No

Geococcus coffeae Green, 1933 [Pseudococcidae] Coffee root mealybug

Yes – Taro is a host. Occurs on the roots of host plants (Ben-Dov et al. 2011).

Yes. Recorded in NT (Ben-Dov 1994), SA, Tas., Vic. and WA (AICN 2011).

No

Halticus insularis Usinger, 1946 [Miridae] Island fleahopper

No – Eggs are laid under leaf cuticle. Nymphs and adults feed on sap (French 2006). Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No


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Hemiberlesia lataniae (Signoret, 1869) [Syn.: Aspidiotus cydoniae Comstock, 1881; Aspidiotus lataniae Signoret, 1869] [Diaspididae] Latania scale

No – Found on upper and lower leaf surfaces, fruits, and stems of host plants (Tenbrick and Hara 1992a). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NSW, Qld, Vic. and WA (AICN 2011).

No

Hemiberlesia palmae (Cockerell, 1893) [Diaspididae] Scale

No – Found on the leaves of hosts (Ben-Dov et al. 2011). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in Qld (AICN 2011).

No

Icerya aegyptiaca (Douglas, 1890) [Monophlebidae] Breadfruit mealybug

No – Feeds on leaves and stems of hosts (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NSW, NT and Qld (AICN 2011).

No

Lamenia caliginea Stål, 1854 [Derbidae] Derbid bug

No – Feeds from leaf tissues. They are often found feeding along the underside midrib of leaves of large-leaved plant hosts (Martin Kessing and Mau 1992). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NSW (APPD 2009).

No

Lepidosaphes carolinensis Beardsley, 1966 [Diaspididae] Caroline scale

Yes – Lepidosaphes spp. are scales usually associated with leaves, stems and fruits of shrubs and trees (CABI 2011). Reported on taro leaf blades and petioles in Micronesia (Nafus 1997).

No record found. Yes – Little information is available on this species. It has limited distribution (Federated States of Micronesia and Palau) and restricted host range (Alocasia sp. and Cycas sp.), suggesting only limited ability to establish.

No – No reports of significant damage to host plants. Nafus (1997) did not consider it a serious pest or of quarantine concern.

No


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Leptoglossus gonagra (Fabricius, 1775) [Syn.: Leptoglossus australis (Fabricius, 1775; Fabrictilis australis (Fabricius, 1775) [Coreidae] Squash bug

No – Feeds on stems, flower buds and developing fruits of hosts (Caetano and Boiça Jr. 2000). Leaf trimming during harvest should exclude this pest from the pathway.


No

Melanaspis bromeliae (Leonardi, 1899) [Diaspididae] Brown pineapple scale

No – Melanaspis spp. are scales usually associated with aerial leaves, stems and fruits of shrubby or tree species (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Myzus persicae (Sulzer, 1776) [Aphididae] Green peach aphid

No – Typically feeds on older senescing leaves, often along the leaf veins (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.


No

Nysius femoratus Van Duzee, 1940 [Lygaeidae] Chinch bug

No – Bugs occasionally reported on taro leaf (French 2006). Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Orosius argentatus (Evans, 1938) [Cicadellidae] Common brown jassid

No – Leaf feeding species. Leaf trimming during harvest should exclude this pest from the pathway.


No

Paraputo aracearum Williams, 2005 [Pseudococcidae] Mealybug

Yes – Found on taro corms imported into California from Fiji in 2004 (Williams 2005).

No record found. Yes – Evidence does not indicate this is an invasive species, but little is known about it. Taro is the only known host, and it has not spread beyond Fiji (Williams 2005).

Yes – Closely related to Paraputo leveri (Williams 2005). Only discovered and described in 2005, and full host range not yet known.

Yes

Paraputo leveri (Green, 1934) [Syn.: Pseudococcus leveri Green, 1934] [Pseudococcidae] Mealybug

Yes – Occurs on the roots of host plants and is attended by ants (Ben-Dov et al. 2011). Intercepted in Hawaii on taro imported from Western Samoa (Williams 2005).

No record found. Yes – Host plants, including mango, grapevine, coffee, taro and fig, are common in Australia. Considered invasive by Williams (2005).

Yes – Host plants include a number of economic crops. A serious pest of coffee in Papua New Guinea (Ben-Dov et al. 2011).

Yes


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Parasaissetia nigra (Nietner, 1861) [Coccidae] Nigra scale

No – Feeds on leaves and stems (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NSW, NT, Qld, Vic. and WA (AICN 2011).

No

Patchiella reaumuri (Kaltenbach, 1843) [Pemphigidae] Taro root aphid

Yes – Extremely damaging pest of dryland taro in Hawaii. Found on roots and base of leaf sheaths. Spread mainly by planting of infested headsetts, but a hot water dip treatment is available to disinfest (Sato and Hara 1997; Sato 2000).

No record found. Yes – Short distance spread is by ants. Long distance spread occurs by movement of planting material, leaves and corms. Aphids feed on the fibrous taro roots, causing them to rot (Carmichael et al. 2008).

Yes – Only known in Hawaii on taro roots, and in Europe on Arum roots and on linden (Tilia) shoots. There is quarantine on transport of planting materials from the island of Hawaii to the other Hawaiian islands (Carmichael et al. 2008).

Yes

Pemphigus sp. [Pemphigidae] Root aphid

No – Reported on taro in Hawaii but not identified to species (Ooka 1994). Feeding activities injure developing roots and can cause plant death (Ooka 1994). Taxonomy is uncertain at species level (Blackman and Eastop 1984). Over 200 records of Pemphigus from the eastern States of Australia, 25 percent unidentified to species, none on taro (APPD 2009). Not likely to be present on corms that have had the roots removed.

Not identified to species. Several Pemphigus species are present in Australia.

No

Pentalonia nigronervosa Coquerel, 1854 [Syn.: Pentalonia caladii Van der Goot, 1917] [Aphididae] Banana aphid

No – Colonies of the banana aphid are commonly found in the upper leaf sheaths and lower flower bracts of host plants. The entire inflorescence may be infested. Small colonies occasionally occur on the leaf blade (Mau et al. 1994). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NSW, NT, Qld and WA (AICN 2011).

No


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Phenacoccus solani Ferris, 1918 [Synonym: Phenacoccus herbarum Lindinger, 1942] [Pseudococcidae] Solanum mealybug

No – Colocasia esculenta is a minor or incidental host of this pest. In other species, infestation is mainly in aerial parts and corms are not known as vehicles for dispersal (see for example Phenacoccus hirsutus, Phenacoccus manihoti (CABI 2011); Phenacoccus glomeratus (French 2006)). Leaf trimming during harvest should exclude this pest from the pathway. The related species Phenacoccus citri will attack potato tubers (CABI 2011).

No record found. No

Pinnaspis buxi (Bouché, 1851) [Diaspididae] Ti scale

No – Feeds on both upper and lower surfaces of leaves (Tenbrick and Hara 1992b). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NT (Ben-Dov et al. 2011).

No

Pinnaspis strachani (Cooley, 1899) [Diaspididae] Hibiscus snow scale

No – Feeds on the stems and leaves of hosts (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in SA (Ben-Dov et al. 2011).

No

Planococcus citri (Risso, 1813) [Pseudococcidae] Citrus mealybug

No – Reports on taro are likely to be misidentifications. There are no records of Planococcus citri on taro or other edible aroids in the Pacific (Macanawai et al. 2005).


No

Planococcus minor (Maskell, 1897) [Pseudococcidae] Pacific mealybug

No – Planococcus minor is a phloem feeder of leaves and stems (Venette and Davis 2004). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in ACT, NSW, NT, Qld and SA (AICN 2011).

No

Pseudococcus longispinus (Targioni Tozzetti, 1867) [Pseudococcidae] Long-tailed mealy bug

No – Found on the stems, fruits and along the veins on the underside of leaves of host plants (CABI 2011).


No


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Pseudococcus orchidicola Takahashi, 1939 [Pseudococcidae] Orchid mealybug

No – Colocasia esculenta is an incidental host of this pest. In other species (e.g. Phenacoccus calceolariae, Phenacoccus comstocki), infestation is mainly in aerial parts, and corms are not known as vehicles for dispersal (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Pulvinaria psidii Maskell, 1893 [Coccidae] Green shield scale

No – Feeds on the leaves and young stems of woody hosts (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.


No

Sophonia rufofascia Kuoh and Kuoh, 1983 [Cicadellidae] Two-spotted leafhopper

No – Primarily a leaf feeder (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Steatococcus samaraius Morrison, 1927 [Monophlebidae] Steatococcus scale

No – Mainly confined to aerial parts of plant (Nelson et al. 2006). Only reported on leaves of taro (Nafus 1997). Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Tarophagus colocasiae (Matsumura, 1920) [Delphacidae] Taro planthopper

Yes – Eggs are laid in small holes in the taro leaf midrib, petioles or petiole bases (Matthews 2003).

Yes. Recorded in Qld (Matthews 2003).

No

Tarophagus persephone (Kirkaldy, 1907) [Delphacidae] Taro planthopper

Yes – Eggs are laid in small holes in the taro leaf midrib, petioles or petiole bases (Matthews 2003).

Yes. Recorded in NT and Qld (Matthews 2003).

No


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Tarophagus proserpina (Kirkaldy, 1907) [Syn.: Megamelus proserpina Kirkaldy, 1907] [Delphacidae] Taro planthopper

Yes – Eggs are laid in small holes in the taro leaf midrib, petioles or petiole bases (Vargo 2000; Matthews 2003).

No record found. Yes – Eggs are laid in petiole bases, so can establish via corms used for planting material. Host plants are common in parts of Australia. Other Tarophagus planthoppers have already established in northern Australia (Matthews 2003).

Yes – Taro planthoppers are important pests of taro (Matthews 2003), but are not likely to affect other crops.

Yes

Lepidoptera (butterflies, moths)

Agrius convolvuli (Linnaeus, 1758) [Syn.: Herse convolvuli (Linnaeus, 1758)] [Sphingidae] Sweet potato hawkmoth

No – Larvae generally eat the younger leaves of hosts, often stripping growing shoots. During major infestations, whole plants may be defoliated (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.


No

Agrotis ipsilon (Hufnagel, 1766) [Noctuidae] black cutworm

No – Feeds on leaves of hosts. Larvae can create 'shotholes' while feeding on tender leaves of seedling plants (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in the ACT, NSW, Qld, Tas. and WA (AICN 2011).

No

Ectropis bhurmitra (Walker, 1860) [Syn.: Boarmia bhurmitra Walker, 1860; Ectropis brevifasciata Wileman, 1912] [Geometridae] Tea twig caterpillar

No – Feeds on leaves (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in Qld under the synonym Ectropis sabulosa (APPD 2009).

No

Helicoverpa armigera (Hübner, 1805) [Noctuidae] Cotton bollworm

No – Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NSW, NT, Qld and WA (Common 1990).

No

Hippotion boerhaviae (Fabricius, 1775) [Sphingidae] Hippotion sphinx moth

No – Larvae of Hippotion spp. feed on leaves, stems and growing points (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NT and Qld (Common 1990).

No


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Hippotion celerio (Linnaeus, 1758) [Sphingidae] Taro hawkmoth

No – Larvae feed on the leaves of the taro plant (Common 1990). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NSW, NT, Qld, SA, Tas., Vic. and WA (Common 1990).

No

Spodoptera litura (Fabricius, 1775) [Syn.: Spodoptera littoralis (Boisduval, 1833)] [Noctuidae] Taro caterpillar

No – Larvae feed on the leaves. Eggs are laid in clusters on the plant (Common 1990). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NSW, NT, Qld, Tas. and WA (Common 1990; AICN 2011).

No

Theretra clotho (Drury, 1773) [Sphingidae] Impatiens hawkmoth

No – Larvae feed on leaves (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in Qld (Common 1990).

No

Theretra oldenlandiae (Fabricius, 1775) [Sphingidae] Impatiens hawkmoth

No – Feeds on leaves, growing tips and flowering heads of hosts, sometimes completely stripping the plant (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NSW, NT, Qld, and WA (Common 1990).

No

Theretra silhetensis (Walker, 1856) [Sphingidae] Narrow-winged sphinx moth

No – Larvae feed on undersides of leaves, and may be found resting on the stem or among the small leaf stems. Eggs are laid singly on both upper and lower leaf surfaces (Pittaway and Kitching 2009). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NT and WA (APPD 2009).

No

Theretra silhetensis subsp. intersecta (Butler, 1875) [Sphingidae] Sphinx moth

No – No specific information on the feeding behaviour of this subspecies found, but likely to be similar to other Theretra silhetensis subspecies that may be present on leaves and stems. Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Has been recorded in eastern Australia (Nielsen et al. 1996).

No

Tiracola plagiata (Walker, 1857) [Noctuidae] Cacao armyworm

No – Larvae feed on leaf surfaces and fruit of hosts. In heavy infestations caterpillars may be found on stems. Pupation occurs in the soil (Weddell 1930).

Yes. Recorded in NSW, NT, Qld and WA (AICN 2011).

No


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Orthoptera (crickets; grasshoppers; katydids)

Hexacentrus mundus (F. Wolker, 1869) [Tettigoniidea] Long-horned cricket

No – Occasional report on taro (French 2006). Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Oxya hyla subsp. intricata (Stål, 1861) [Acrididae] Short-horned grasshopper

No – Leaf feeder. Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Teleogryllus oceanicus (Le Guillou, 1841) [Gryllidae] Oceanic field cricket

No – Nymphs and adults feed on growing shoots and buds. Field crickets shelter in the soil, but emerge to feed at night (Sallam et al. 2007).

Yes. Recorded in NT and WA (AICN 2011).

No

Zonocerus elegans (Thunberg, 1815) [Pyrgomorphidae] Elegant grasshopper

No – External leaf feeder, congregating on upper parts of plant (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Zonocerus variegatus (Linnaeus, 1758) [Pyrgomorphidae] Variegated grasshopper

No – External leaf feeder, congregating on upper parts of plant (CABI 2011). Leaf trimming during harvest should exclude this pest from the pathway.

No record found. No

Thysanoptera (thrips)

Caliothrips striatopterus (Kobus, 1893) [Thripidae] Black thrips of maize

No – Feeds on leaves. Thrips of the subfamily Panchaetothripinae are generally associated with older leaves rather than new foliage (Mound 2008). Leaf trimming during harvest should exclude this pest from the pathway.

Yes. Recorded in NSW, NT, Qld and WA (CSIRO 2009).

No

NEMATODA: Secernetea

Tylenchida

Aphelenchoides besseyi Christie, 1942 [Aphelenchoididae] Rice leaf nematode

No – Ectoparasitic feeders on growing points of leaves and stems. Does not survive for long periods in the soil (EPPO 2011b).

Yes. Recorded in NT and Qld (EPPO 2011b; McLeod et al. 1994).

No


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Aphelenchoides bicaudatus (Imamura, 1931) [Aphelenchoididae]

No – Aphelenchids, including Aphelenchoides bicaudatus, are predominantly free-living mycetophagous nematodes (Manzanilla-Lopez et al. 2004). Orton Williams (1980) reported this nematode occurring in small numbers in association with taro, but did not provide details of which part of the plant, if any, were affected. Cleaning of all soil from corms will remove this nematode from the pathway.

Yes. Recorded in NSW, Qld, Vic. and WA (McLeod et al. 1994).

No

Aphelenchus avenae Bastian, 1865 [Aphelenchoididae]

No – Aphelenchus avenae feeds on the hyphae of soil fungi (Ishibashi et al. 2005; CABI 2011). Association with taro plant is unclear, but possibly present in soil amongst roots. Cleaning of all soil from corms will remove this nematode from the pathway.

Yes. Recorded in NSW, NT, Qld, SA, Vic. and WA (McLeod et al. 1994).

No

Caloosia longicaudata (Loos, 1948) [Syn.: Hemicycliophora longicaudata Loos, 1948] [Caloosiidae] Ring nematode

No – May be present in the soil around the taro plant feeding on the roots, but not likely to present on or in the corm.

No record found. No

Criconema polynesianum (Orton Williams, 1982) [Syn.: Nothocriconema polynesianum Orton Williams, 1982] [Criconematidae] Ring nematode

No – An ectoparasitic nematode that feeds on the root cortex (Siddiqi 2000). May be present in the soil around the taro plant feeding on the roots, but not likely to present on or in the corm.

No record found. No


136




Criconemella denoudeni (de Grisse, 1967) [Syn.: Macroposthonia denoudeni de Grisse, 1967] [Criconematidae] Ring nematode

Yes – Migratory ectoparasitic nematode that feeds on the root cortex (Siddiqi 2000). Association with taro seems to be minor.

No record found. Yes – This nematode is polyphagous and has been recorded on more than 65 plant hosts (Orton Williams 1980), many of which are present in Australia.

No – Ring nematodes are only considered to be a nuisance on certain crops when large populations build up (Siddiqi 2000). Not listed as a major pest in Luc et al. (1990) or Bridge (1988).

No

Discocriconemella limitanea (Luc, 1959) [Criconematidae] Ring nematode


Yes. Recorded in NSW and Qld (McLeod et al. 1994).

No

Gracilacus aonli (Misra & Edward, 1971) [Syn.: Paratylenchus aonli Misra & Edward, 1971] [Paratylenchidae]

No – Reported feeding on the roots of taro in Fiji (Orton Williams 1985). May be present in the soil around the taro plant feeding on the roots, but not likely to present on or in the corm.

No record found. No

Helicotylenchus crenacauda Sher, 1966 [Hoplolaimidae] Spiral nematode

No – May be present in the soil around the taro plant feeding on the roots, but not likely to present on or in the corm. Orton Williams (1980) reported this species occasionally found in taro plots in Fiji.

No record found. No

Helicotylenchus dihystera (Cobb, 1893) [Hoplolaimidae] Spiral nematode

Yes – Helicotylenchus spp. are endo-, semiendo- or ecto-parasites of roots, including taro (Luc et al. 1990).


No

Helicotylenchus erythrinae (Zimmerman, 1904) [Hoplolaimidae] Spiral nematode

Yes – Helicotylenchus spp. are endo-, semiendo- or ecto-parasites of roots. This species has been reported as associated with taro in Fiji (Kirby et al. 1980).

Yes. Recorded in Qld and SA (McLeod et al. 1994).

No


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Helicotylenchus indicus Siddiqi, 1963 [Syn.: Helicotylenchus microdorus Prasad, Khan & Chawla, 1965; Helicotylenchus teres Gaur & Prasad, 1973] [Hoplolaimidae] Spiral nematode

Yes – Helicotylenchus spp. are endo-, semiendo- or ecto-parasites of roots, including taro (Luc et al. 1990). Causes some damage to vegetable crops in India, but only when in high numbers (Lamberti 1997).

No record found. Yes – Helicotylenchus spp. are endo-, semiecto- or ecto-parasites of roots, including taro. Helicotylenchus spp. are known to be amphimictic and mitotically parthenogenic (Evans 1998).

No – A population build-up of this species around sapodilla roots (Manilkara zapota) was reported by Saeed (1974). Not listed as a damaging nematode of taro by Luc et al. (1990).

No

Helicotylenchus microcephalus Sher, 1966 [Syn.: Helicotylenchus belurensis Singh & Khera, 1980] [Hoplolaimidae] Spiral nematode

Yes – Helicotylenchus spp. are endo-, semiendo- or ecto-parasites of roots, including taro. Listed as an actionable regulated pest for fresh green beans from South Africa by New Zealand (NZ MAF 1999).


Yes – Reported as potentially important root parasites of banana and plantain by Bridge (1988) and Luc et al. (1990), and the cause of root necrosis and stunted growth of bananas in the Pacific. The more serious banana pathogen Helicotylenchus multicinctus and other Helicotylenchus spp. are already present in Australia (McLeod et al. 1994; Sauer 1981).

Yes

Helicotylenchus mucronatus Siddiqi, 1963 [Hoplolaimidae] Spiral nematode



Yes – Reported as potentially important root parasites of banana and plantain by Bridge (1988) and Luc et al. (1990), and the cause of root necrosis and stunted growth of bananas in the Pacific. The more serious banana pathogen Helicotylenchus multicinctus and other Helicotylenchus spp. are already present in Australia (McLeod et al. 1994; Sauer 1981).

Yes

Helicotylenchus multicinctus (Cobb, 1893) [Syn.: Tylenchorhynchus multicinctus (Cobb, 1893); Tylenchus multicinctus Cobb, 1983] [Hoplolaimidae] Spiral nematode


Yes. Recorded in NSW, NT, Qld, SA and WA (McLeod et al. 1994; Sauer 1981).

No

Hemicriconemoides cocophilus (Loos, 1949) [Criconematidae]


Yes. Recorded in NT, Qld and WA (McLeod et al. 1994).

No


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Hirschmanniella miticausa Bridge, Mortimer & Jackson, 1983 [Pratylenchidae] Taro nematode

Yes – Causes a serious red necrosis in taro corms, rendering them inedible. A quarantine pest in South East Asia and the Pacific Islands. Presently confined to Papua New Guinea (restricted distribution) and Solomon Islands (Bridge 1988).

No record found. Yes – A migratory endoparasite of the corm. Lower corm most severely affected, rarer in middle and upper parts. Less commonly found in roots. Spread by planting of infected corms, but also spread in water (CABI 2011).

Yes – Causes a serious red necrosis in taro corms, rendering them inedible. Presently confined to Papua New Guinea (restricted distribution) and Solomon Islands (CABI 2011).

Yes

Hoplolaimus indicus Sher, 1963 [Syn.: Basirolaimus indicus (Sher, 1963); Hoplolaimus arachidis Maharaju & Das, 1982] [Hoplolaimidae] Lance nematode

No – Only one record of this nematode in association with taro (Bridge and Page 1984). May be present in the soil around the taro plant feeding on the roots, but not likely to present on or in the corm.

No record found. No

Hoplolaimus seinhorsti Luc, 1958 [Hoplolaimidae] Lance nematode


Yes. Recorded in NT, Qld and WA (McLeod et al. 1994).

No

Longidorus pisi Edward, Misa & Singh, 1964 [Syn.: Longidorus siddiqii Aboul-Eid, 1970] Longidoridae] Needle nematode

Yes – Reported on the roots of taro in India (as Longidorus siddiqii) (Prabha 1973).

No record found. Yes – This species has a wide geographical distribution and has been recorded on a number of host plants.

No – Economic damage has not been reported, although the nematode has been associated with a number of important plant hosts including maize (Van den Oever et al. 1998), eggplant (Yousef and Jacob 1994), grapevine (Choleva et al. 1991) and peanuts (Venter et al. 1992). Speculation that Longidorus siddiqii is associated with clump disease in peanut (Merny and Mauboussin 1973) does not appear to have been substantiated.

No


139




Longidorus sylphus Thorne, 1939 [Longidoridae] Needle nematode

Yes – Has been reported on taro in Hawaii (Ooka 1994).

No record found. Yes – Longidorus spp. exhibit parthenogenic reproduction (Evans 1998). This has led to clonal speciation, and some disagreement on species limits. Some authorities include Longidorus sylphus within a broad Longidorus elongatus, but most keep them separate.

Yes – A pest, particularly of mint (Mentha spp.), maize (Zea) and grapevine (Vitis) roots (Ferris 1999). Has been reported on taro in Hawaii but no data is available on damage caused (Ooka 1994). Risk is mainly to crops other than taro. Longidorus spp. are migratory ectoparasites, remaining outside roots and feeding via their protrusible stylet. Tissue damage is usually minimal except in high density infections (Hussey and Grundler 1998) or where root tips are attacked (Luc et al. 1990).

Yes

Mesocriconema onoensis (Luc, 1959) Loof & De Grisse, 1989) [Syn.: Criconemella onoensis (Luc, 1959); Macroposthonia onoensis (Luc, 1959)] [Criconematidae] Ring nematode

Yes – Has been reported on taro in Fiji (Orton Williams 1980). Association with taro seems to be minor.

Yes. Recorded in NT and Qld (McLeod et al. 1994; Stirling et al. 2001).

No

Meloidogyne arenaria (Neal, 1889) [Heteroderidae] Peanut root-knot nematode


Yes. Recorded in NSW, Qld, SA, Tas., Vic. and WA (McLeod et al. 1994).

No

Meloidogyne graminicola Golden & Birchfield, 1965 [Heteroderidae] Rice root knot nematode

No – Taro is reported as a host (Luc et al. 1990). May be present in the soil around the taro plant feeding inside the roots, but not likely to present on or in the corm. Infested soil is a greater risk than corms. Second-stage juveniles invade the roots, just behind the root tips and may migrate within the root cortex (Luc et al. 1990).

No record found. No

Meloidogyne hapla Chitwood, 1949 [Heteroderidae] Root-knot nematode



No


140




Meloidogyne incognita (Kofoid & White, 1919) [Heteroderidae] Root-knot nematode


Yes. Recorded in NSW, NT, Qld, SA, Tas., Vic. and WA (McLeod et al. 1994).

No

Meloidogyne javanica (Treub, 1885) [Heteroderidae] Sugarcane eelworm


Yes. Recorded in ACT, NSW, NT, Qld, SA, Tas., Vic. and WA (McLeod et al. 1994).

No

Ogma melanesicum (Andrassy, 1979) [Syn.: Syro melanesicus (Andrassy, 1979)] [Criconematidae]

No – Reported feeding on roots of taro in Samoa (Orton Williams 1985). May be present in the soil around the taro plant feeding on the roots, but not likely to present on or in the corm.

Yes. Recorded in WA (as Ogma melanesica) (McLeod et al. 1994).

No

Pratylenchus brachyurus (Godfrey, 1929) [Pratylenchidae] Root-lesion nematode

Yes – Migratory endoparasite of roots. The nematode tunnels through the root cortex as it feeds. In some hosts it can enter the plant’s vascular system (Payan 1989). Reported from taro in Fiji, Samoa and Tonga (Orton Williams 1980).

Yes. Recorded in NSW, NT, Qld and WA (McLeod et al. 1994).

No

Pratylenchus coffeae (Zimmermann, 1898) [Pratylenchidae] Banana root nematode

Yes – Reported from taro in Fiji (Orton Williams 1980). Mainly found in the roots and in the soil, but some Pratylenchus coffeae nematodes may also be present in the corm skin (Luc et al. 1990). Nematodes may be present on poorly cleaned taro corms.

Yes. Recorded in northern Australia, NSW, Qld, SA, Vic. and WA (McLeod et al. 1994).

No

Pratylenchus penetrans (Cobb, 1917) [Pratylenchidae] Northern root lesion nematode

Yes – Pratylenchus spp. mainly feed on the root cortical tissues, but they are known to also attack potato and yam tubers, resulting in surface lesions (Luc et al. 1990). Nematodes may be present on poorly cleaned taro corms.


No


141




Pratylenchus pratensis (deMan, 1880) Filipjev, 1936 [Pratylenchidae] Lesion nematode

Yes – Reported on taro in Egypt (Ibrahim et al. 2010). Pratylenchus spp. mainly feed on the root cortical tissues, but they are known to also attack potato and yam tubers, resulting in surface lesions (Luc et al. 1990). Nematodes may be present on poorly cleaned taro corms.

Yes. Recorded in NSW and Vic. (McLeod et al. 1994).

No

Pratylenchus zeae Graham, 1951 [Pratylenchidae] Root-lesion nematode

Yes – Reported from taro in Fiji (Orton Williams 1980). Pratylenchus spp. mainly feed on the root cortical tissues, but they are known to also attack potato and yam tubers, resulting in surface lesions (Luc et al. 1990). Nematodes may be present on poorly cleaned taro corms.

Yes. Recorded in NSW, NT, Qld, Vic. (McLeod et al. 1994) and WA (Riley and Kelly 2002).

No

Radopholus similis (Cobb, 1893) [Pratylenchidae] Burrowing nematode; Banana root nematode

Yes – Radopholus spp. are migratory endoparasites of root and corm tissues (Luc et al. 1990). Reported on taro in Fiji and Samoa (Orton Williams 1980).

Yes. Recorded in NSW, NT, Qld, SA and WA (McLeod et al. 1994; EPPO 2011c).

No

Rotylenchulus reniformis Linford & Oliveira, 1940 [Syn.: Tetylenchus nicotiana Yokoo & Tanaka, 1954; Rotylenchulus nicotiana (Yokoo & Tanaka, 1954] [Hoplolaimidae] Reniform nematode

No – Rotylenchulus spp. are sedentary root feeding nematodes (Luc et al. 1990). Not expected to feed on corm tissues. Reported on taro in Fiji, Samoa, Solomon Islands and Tonga (Orton Williams 1980).

Yes. Recorded in NT and WA (Sauer 1981).

No

Scutellonema bradys (Steiner & Le Hew, 1933) Andrassy, 1958 [Hoplolaimidae] Yam nematode

Yes – Scutellonema bradys has been reported on taro in the Caribbean, so could potentially be present on corms from that region. However, taro is considered to be a poor host (Bridge et al. 2005), so this nematode is unlikely to be commonly associated with imported taro corms.

No record found. No – This nematode is unlikely to establish via trade in taro corms. While small numbers can survive on some plant hosts for short periods, populations only thrive and increase on yams, cowpea, melon and sesame (Bridge et al. 2005). It mostly spreads via movement of yam tubers for planting (CABI 2011).

No


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Tylenchulus semipenetrans Cobb, 1913 [Tylenchulidae] Citrus root nematode

No – Tylenchulus spp. are sedentary root feeding nematodes (Luc et al. 1990). Not expected to feed on corm tissues.


No

Xiphinema brevicolle Lordello & Da Costa, 1961 [Longidoridae] Dagger nematode


Yes. Recorded in NSW, Qld, Vic. and WA (McLeod et al. 1994).

No

Xiphinema elongatum Schuurmans Stekhoven & Teunissen, 1938 [Longidoridae] Dagger nematode



No

Xiphinema ensiculiferum (Cobb, 1893) [Syn.: Tylencholaimus ensiculiferus Cobb, 1893] [Longidoridae] Dagger nematode


Yes. Recorded in NSW and Qld (McLeod et al. 1994).

No

Xiphinema insigne Loos, 1949 [Syn.: Xiphinema indicum Siddiqi, 1959] [Longidoridae] Dagger nematode



No

BACTERIA

Bacillus megaterium De Bary, 1884 Yes – Reported on taro in the Solomon Islands (McKenzie and Jackson 1986).

Yes. Recorded in Australia (CABI 2011).

No

Bacillus subtilis (Ehrenberg, 1835) Cohn, 1872

Yes – Reported on taro in the Solomon Islands (McKenzie and Jackson 1986).

Yes. Recorded in NSW, Qld and SA (APPD 2009).

No

Erwinia carotovora subsp. carotovora (Jones, 1901) Bergey et al., 1923 Bacterial root rot of sweet potato

Yes – Reported on taro in French Polynesia (Hammes et al. 1989), Papua New Guinea (Muthappa 1987) and Solomon Islands (McKenzie and Jackson 1986).

Yes. Recorded in NSW (Letham 1995), Qld, Vic. (APPD 2009), NT, Tas. and WA (CABI 2011).

No


143




Dickeya sp. [Syn.: Erwinia chrysanthemi (Burkh.) Young et al., 1978] Bacterial soft rot

Yes – Causes a storage rot in taro corms (Jackson and Gollifer 1975).

Not verified but likely. Soft rot identified as Erwinia chrysanthemi has been reported in taro crops in Queensland (Daniells et al. 2009).

Yes – Bacteria survive in the soil. Other closely related strains or species are already present and widespread in Australia. Taro host plants are common in parts of Australia.

No – Only a minor problem in the field. It has little effect on the number of corms produced or the development of corm rots in healthy plants, but can be a problem in wounded corms (Daniells et al. 2009). Predominantly a secondary storage rot (Jackson and Gollifer 1975). The pathogen associated with taro in the Solomon Islands is phylogenetically distinct from the disease of pineapple and potato (Dickeya zeae) (Parkinson et al. 2009).

No

Xanthomonas axonopodis pv. dieffenbachiae (McCulloch & Pirone, 1939) Vauterin et al., 1995 Bacterial blight of aroids

Yes – The bacterium is in the leaves and in decaying dead leaf material in the soil. However, infection may be systemic, and bacteria may be present in the corm tissues.

No. A strain of Xanthomonas axonopodis has been recorded in Qld on glycine (Neonotonia wightii) (APPD 2009). No record of the strain associated with taro in Australia.

Yes – Suitable host plants are present in many parts of northern Australia. While the strains affecting taro have relatively narrow host ranges, they may be able to infect other Araceae species.

Yes – Leaf blight disease caused extensive damage to a taro crop in India (Phookan et al. 1996).

Yes

CHROMALVEOLATA

Peronosporales (Albugo, Phytophthora)

Peronospora trichotoma Massee Corm rot

No – Type specimen collected on taro in Jamaica in 1886, but other records of this species do not appear to exist. Peronospora trichotoma is probably based on a hyphomycete that may have overgrown an initial attack of Phytophthora colocasiae (Constantinescu 1991).

No record found. No

Phytophthora botryosa Chee Phytophthora leaf fall

No – Primarily a disease of rubber trees, causing premature leaf fall. Only one record associated with taro (CABI 2011). There is no evidence to suggest corms are infected by or are likely to carry infectious propagules. Trimming of leaves during harvest and the cleaning of soil from corms will remove Phytophthora botryosa chlamydospores from the pathway.

No record found. No


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Phytophthora cinnamomi Rands Root rot

Yes – Reported causing root and corm rot in taro in Fiji (Dingley et al. 1981).

Yes. Recorded in NSW (Letham 1995), Qld (Simmonds 1966), SA (Cook and Dube 1989), Tas. (Sampson and Walker 1982) and WA (Shivas 1989).

No

Phytophthora colocasiae Raciborski Taro leaf blight

Yes – Pathogen survives as mycelium in corm until replanted. Oospores may also survive in corm and leaf tissue (CABI 2011). Reported causing taro corm rots in the Solomon Islands (Jackson and Gollifer 1975).

No record found. Yes – Primarily a foliar pathogen, but petioles and corms can be infected (Brooks 2005). Mycelium in corms is thought to be a pathway for transmission, although Phytophthora colocasiae also causes fast developing (5-10 days) hard corm rots (Brooks 2005). Although the species is heterothallic, oospore development has not been demonstrated in nature, and reproduction is by mycelium and zoospores.

Yes – Crop losses of 30-50 percent are reported from affected countries (Brooks 2005).

Yes

Phytophthora nicotianae Breda de Haan Black shank

Yes – Reported causing root and corm rot in taro in Fiji (Dingley et al. 1981).


No

Phytophthora palmivora (E.J. Butler) E.J. Butler Budrot

Yes – Reported on taro in French Polynesia (Hammes et al. 1989).

Yes. Recorded in NSW (Letham 1995) and Qld (Simmonds 1966).

No

Phytophthora sp. (not yet defined at species level) Taro pocket rot

Yes – A slow growing rot formed near the top of the corm. It is homothallic, and forms thick-walled sexual spores which may persist in paddies for long periods (CTAHR 2002).

No record found. Yes – Early stages of the disease are hard to spot, and the rot is slow growing. The species is self-fertile and will form thick-walled sexual spores that can remain in the soil for long periods (CTAHR 2002).

Yes – Only known in Hawaii on taro. Caused severe crop damage from mid-1990s (Uchida 1998). Similar rots can be caused by Phytophthora colocasiae (CTAHR 2002).

Yes


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Pythium adhaerens Sparrow Corm soft rot

Yes – Taro has been recorded as a host in Palau (McKenzie and Jackson 1990). No specific data available, but mode of action similar to Pythium carolinianum.

No record found. Yes – Similar to Pythium carolinianum (below).

No – Not considered to be of economic importance (AQIS 1999).

No

Pythium aphanidermatum (Edson) Fitzpatrick Damping off

Yes – Taro is reported as a host in the Federated States of Micronesia (Ecoport 2011) and Samoa (Gerlach 1988).

Yes. Recorded in NSW (Letham 1995), Qld (Simmonds 1966), SA (Cook and Dube 1989) and WA (Shivas 1989).

No

Pythium arrhenomanes Drechsler Root rot

Yes – Reported causing taro corm rot in the Cook Islands (Dingley et al. 1981).

Yes. Recorded in NSW (Cother and Gilbert 1992) and Qld (Simmonds 1966).

No

Pythium carolinianum V.D. Matthews Root rot, Corm soft rot

Yes – Rots usually start with roots but spread to corm, and can be transmitted by planting of infected corms (Jackson and Gerlach 1985; Carmichael et al. 2008). The pathogen may invade the corm through cuts and harvesting damage (Erwin and Ribeiro 1996)

No record found. Yes – Has been reported to have a minimum, optimal and maximum growth at 10 °C, 30 °C and more than 40 °C respectively (Abdelzaher and Elnaghy 1998), so could establish in parts on northern Australia.

Yes – Both wetland and dryland taro crops are affected, the former most severely (Carmichael et al. 2008). Crop losses range from 10-100 percent with an average of about 25 percent (Jackson and Gerlach 1985).

Yes

Pythium debaryanum R. Hesse Damping-off


Yes, Recorded in Qld (Simmonds 1966), SA (Cook and Dube 1989), Tas. (Sampson and Walker 1982) and WA (Shivas 1989).

No

Pythium deliense Meurs Damping-off

Yes – Reported on taro in Samoa (Gerlach 1988).

Yes. Recorded in Qld (Vawdrey and Peterson 1990) and Tas. (Sampson and Walker 1982).

No

Pythium graminicola Subramaniam Root rot

Yes – Reported causing taro corm rot in Hawaii (Raabe et al. 1981).

Yes. Recorded in NSW, Qld (APPD 2009) and SA (Cook and Dube 1989).

No


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Pythium irregulare Buisman Dieback

Yes – Reported causing corm rot in the Cook Islands (Dingley et al. 1981) and French Polynesia (Hammes et al. 1989).


No

Pythium middletonii Sparrow Damping-off

Yes – Reported causing corm rot in the Cook Islands (Dingley et al. 1981), Palau (McKenzie and Jackson 1990), Samoa (Gerlach 1988) and the Solomon Islands (McKenzie and Jackson 1986).

Yes. Recorded in NSW (Letham 1995), Tas. (Sampson and Walker 1982) and WA (Shivas 1989).

No

Pythium myriotylum Drechsler Brown rot



No

Pythium splendens Hans Braun [Including: Pythium splendens var. hawaianum Sideris; Pythium splendens Hans Braun var. splendens] Blast

Yes – Reported causing taro corm rot in Fiji, Samoa (Dingley et al. 1981) and the Solomon Islands (McKenzie and Jackson 1986).

Yes. Recorded in Qld (Simmonds 1966), SA (Cook and Dube 1989), Tas. (Sampson and Walker 1982) and WA (Shivas 1989).

No

Pythium ultimum Trow Pythium rot

Yes – Soil pathogen responsible for root and corm rots. May be present in infected corms.


No

Pythium vexans de Bary [Including: Pythium vexans var. minutum G.S. Mer & Khulbe; Pythium vexans de Bary var. vexans]

Yes – Reported causing taro corm rot in Fiji (Dingley et al. 1981), Samoa (Gerlach 1988) and Solomon Islands (McKenzie and Jackson 1986).


No


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FUNGI

Acremonium zonatum (Sawada) W. Gams

No – Pathogen reported causing leaf spot on taro in Samoa (Dingley et al. 1981). Unlikely to be present on fresh corms.

Yes. Recorded in Qld (Galbraith 1987).

No

Allomyces arbusculus Butler

No – Recorded as associated with taro in Hawaii by Raabe et al. (1981). Saprophytic on plant and animal debris, but unlikely to be on fresh corms (Ecoport 2011).

No record found. No

Apiospora montagnei Saccardo, [Syn.: Tubercularia apiospora Durieu & Montagne]

Yes – Not a primary plant pathogen, but known to be a secondary invader or saprophyte, so may arrive with poorly cleaned or damaged corms (Kirk 1991).

Yes. Recorded in Qld (Frohlich et al. 1997).

No

Armillaria mellea (Vahl: Fr.) P. Kumm.

No – Reported causing secondary infection of Colocasia antiquorum in Ghana (Farr and Rossman 2011). While Armillaria mellea is known as a root pathogen, it is typically associated with hardwood trees and conifer hosts, as well as decaying wood. Unlikely to be on fresh corms.

No. Older Australian records (e.g. Simmonds 1966) are likely to be misidentifications.

No

Aspergillus aculeatus Iizuka

Yes – Soilborne fungus often associated with decaying plant material. Reported on taro in the Solomon Islands (McKenzie and Jackson 1986).

Yes. Recorded in NSW, Qld and SA (Leong 2005).

No

Aspergillus niger Tieghem Collar rot

Yes – Aspergillus niger infection results in storage rots in corms of Colocasia spp. (Ugwuanyi and Obeta 1996).

Yes. Recorded in NSW, Qld, SA, Tas., Vic. and WA (Leong 2005).

No

Aspergillus restrictus G.Sm Fruit rot

Yes – Storage mould of grains, but also likely to affect taro corms stored in damp conditions.

Yes. Recorded in Qld (Upsher and Upsher 1995) and Vic. (APPD 2009).

No

Athelia rolfsii Curzi (see Sclerotium rolfsii)


148




Botrytis cinerea Pers. : Fr. Grey mould

Yes – The fungus attacks all parts of the plant, and is particularly a problem in postharvest storage (CABI 2011).

Yes. Recorded in Qld (Simmonds 1966), SA (Cook and Dube 1989), Tas. (Sampson and Walker 1982) and WA (Shivas 1989).

No

Ceratocystis fimbriata Ellis & Halsted Ceratocystis blight

Yes – Reported causing taro corm rot in Fiji and Samoa (Dingley et al. 1981).

Yes. Recorded in SA (Cook and Dube 1989) and WA (Shivas 1989).

No

Ceratocystis paradoxa (Dade) C. Moreau sens. lat. Black rot

Yes – Reported causing taro corm rot in Samoa (Dingley et al. 1981).

Yes. Recorded in NSW (Magee and McCleery 1937) and Qld (Simmonds 1966).

No

Cercospora colocasiae (Höhnel) Chupp - see Passalora colocasiae

Choanephora cucurbitarum (Berkeley & Ravenel) Thaxt. Choanephora fruit rot

No – Only affects the taro leaves. In severe cases the petioles may also be affected causing the leaf to collapse as a rotten pulpy mass. Often a secondary pathogen following infection by Phytophthora colocasiae (Sinha 1940). Spores may be present in the soil.

Yes. Present in NT (O’Gara 1998).

No

Cladosporium cladosporioides (Fresenius) G.A. de Vries (see Mycosphaerella tassiana)

Cladosporium colocasiae Sawada Ghost spot

Yes – Mainly affects the leaves, which can become severly diseased, but also spreads to the petioles (Awuah 1995).

Yes. Recorded in NSW and Qld (APPD 2009).

No

Cladosporium colocasiicola Sawada Leaf blight

No – Recorded as associated with taro in American Samoa (Brooks 2006). It is a leaf pathogen, causing brown circular lesions (Sawada 1959).

No record found. No


149




Cladosporium oxysporum Berkeley & M.A. Curtis Seed rot

No – Pathogen associated with the taro foliage, but may be present in the soil as a saprobe.

Yes. Recorded in NSW and Qld (Willingham et al. 2002).

No

Cochliobolus geniculatus R.R. Nelson Seedling blight

No – More saprophytic than parasitic, typically occurring on senescing, heat stressed leaves (Sivanesan and Holliday 1998).

Yes. Recorded in Qld (Hyde and Alcorn 1993) and WA (Shivas 1989).

No

Cochliobolus lunatus R.R.Nelson & Haasis [Syn.: Curvularia lunata (Wakker) Boedijn 1933] Head mould

No – Predominantly a pathogen of foliage and floral structures, but can survive in the soil in crop residues (CABI 2011). Reported on taro in New Caledonia (Ecoport 2011).

Yes. Recorded in NSW (Letham 1995), Qld (Hyde and Alcorn 1993) and WA (Shivas 1989).

No

Colletotrichum capsici (Syd.) E.J. Butler & Bisby Leaf spot

No – Leaf pathogen affecting the aerial parts of host plants (CABI 2011). Reported on taro in the Solomon Islands (McKenzie and Jackson 1986).

Yes. Recorded in WA (Shivas 1989).

No

Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. Root rot

Yes – A common saprobe and opportunistic invader of dead or damaged plant material (CABI 2011). May be present on damaged or poorly washed corms.

Yes. Recorded in Qld (Hyde and Alcorn 1993; Simmonds 1966), SA (Cook and Dube 1989), Tas. (Sampson and Walker 1982) and WA (Shivas 1989).

No

Corallomycetella repens (Berkeley & Broome) Rossman & Samuels [Syn.: Sphaerostilbe repens Berkeley & Broome, Nectria mauritiicola (Hennings) Seifert & Samuels] Anamorph: Rhizostilbella hibisci (Patouillard) Seifert. Violet root rot

Yes – Reported on taro in French Polynesia (Hammes et al. 1989) and the Malay Peninsula (Thompson and Johnston 1953) and is likely to infect the corms.

Reported as a possible mycorrhizal symbiont of an introduced orchid in southern Western Australia (Bonnardeaux et al. 2007).

Yes – The fungus is primarily saprophytic, but under anaerobic waterlogged conditions can attack root tissues.

Yes – A minor pest of taro, but more serious on tree crops such as rubber, citrus, coffee, mango etc. grown in waterlogged conditions.

Yes

Curvularia fallax Boedijn

No – Causes disease of inflorescences and foliage, but can survive in soil (CABI 2011). Reported on taro in the Solomon Islands (McKenzie and Jackson 1986).

Yes. Recorded in Qld (Hyde and Alcorn 1993).

No


150




Curvularia pallescens Boedijn 1933 [Syn.: Curvularia leonensis M.B. Ellis] Leaf spot

No – Mainly a leaf pathogen, but can cause rots in other tissues (Farr and Rossman 2011).


No

Curvularia senegalensis (Spegazzini) Subram.

Yes – Associated with corm rot of taro (Ecoport 2011). Reported on taro in the Solomon Islands (McKenzie and Jackson 1986).

Yes. Recorded in Qld and Vic. (Upsher and Upsher 1995).

No

Epicoccum sorghi (Sacc.) Aveskamp, Gruyter & Verkley [Syn.: Phoma sorghina (Sacc.) Boerema, Dorenb. & Kesteren]

Yes – An opportunistic soilborne pathogen that may be present on damaged or poorly washed corms.


No

Exserohilum rostratum (Drechsler) K.J. Leonard & Suggs [Syn.: Drechslera rostrata (Drechsler) M.J. Richardson & E.M. Fraser] Leaf spot

No – Leaf pathogen causing leaf spots, blight and rots (Forsberg 1985).

Yes. Recorded in Qld (Forsberg 1985; Hyde and Alcorn 1993) and WA (Shivas 1989).

No

Fusarium chlamydosporum Wollenw. & Reinking

Yes – Saprophytic soilborne fungus that may be present on damaged or poorly washed corms.


No

Fusarium lichenicola C. Massal. [Syn.: Cylindrocarpon lichenicola (C. Massal.) D. Hawksw.]


Yes. Present in Australia (Brayford 1987).

No

Fusarium oxysporum Schlechtendal. Basal rot

Yes – Fusarium oxysporum infection results in storage rots in corms of Colocasia spp. (Ugwuanyi and Obeta 1996).


No

Fusarium pallidoroseum (Cooke) Saccardo. Fungal gummosis


No


151




Fusarium roseum Link (see Gibberella zeae (Schweinitz) Petch)

Fusarium solani (Mart.) Saccardo (see Nectria haematococca) Dry rot

Geotrichum candidum Link Sour rot

Yes – Geotrichum candidum infection results in storage rots in corms of Colocasia spp. (Ugwuanyi and Obeta 1996).

Yes. Recorded in NSW (Letham 1995), SA (Cook and Dube 1989), Tas. (Sampson and Walker 1982) and WA (Shivas 1989).

No

Gibberella intricans Wollenweber Damping-off

Yes. Recorded in Qld (Simmonds 1966), and WA (Shivas 1989).

No

Gibberella zeae (Schweinitz) Petch [Syn.: Fusarium roseum Link] Blight

Yes. Recorded in Qld (Simmonds 1966), SA (Cook and Dube 1989), Vic. (Cunnington 2003) and WA (Shivas 1989).

No

Glomerella cingulata (Stoneman) Spaulding & H. Schrenk Anthracnose

Yes. Recorded in NSW (Letham 1995), Qld (Simmonds 1966; Hyde and Alcorn 1993), SA (Cook and Dube 1989), Tas. (Sampson and Walker 1982), Vic. (Cunnington 2003) and WA (Shivas 1989).

No


152




Khuskia oryziae Huds. [Syn.: Nigrospora oryzae (Berkeley & Broome) Petch] Cob rot

Yes. Recorded in NSW (Letham 1995), SA (Cook and Dube 1989) and WA (Shivas 1989).

No

Lasiodiplodia theobromae (Patouillard) Griffiths & Maublanc [Syn.: Botryodiplodia theobromae Patouillard] Diplodia pod rot

Yes – Reported causing rot of taro corms in Samoa (Dingley et al. 1981). Infection results in postharvest rot of corms (Carmichael et al. 2008).

Yes. Recorded in NSW (Letham 1995), Qld (Simmonds 1966) and WA (Shivas 1989).

No

Leptosphaerulina trifolii (Rostovzev) Petrak White spot of taro

No – Causes spotting on taro leaves that may result in shothole symptoms (Carmichael et al. 2008). Unlikely to be present on fresh corms.


No

Marasmiellus colocasiae Capelari & Antonín

Yes – Isolated from infected corms in Brazil (Capelari et al. 2010).

No record found. Little is known about this recently described species, so the potential for establishment and spread in Australia is unknown. However, given that related species and host plants are present in Australia, it is assumed there is some potential for establishment and spread.

Yes – Losses in crop production up to 100 percent in a 2 hectare plot in Brazil were attributed to this fungus (Capelari et al. 2010)

Yes

Marasmiellus stenophyllus (Montagne) Singer Corm and leaf rot

Yes – This pathogen infects taro at the base of the plant, affecting corms and roots. Mycelium grows over the corm (Carmichael et al. 2008).

Yes. Recorded in Qld (Simmonds 1966).

No

Mycosphaerella alocasiae Sydow & Paul Sydow Anamorph: Passalora colocasiae, q.v

Small round leaf spot

No – Common on giant taro (Alocasia macrorrhiza), but rare on taro and reports may be the result of host misidentification. Only oldest leaves are affected and damage is minor (Ecoport 2011). Removal of leaves at harvest should eliminate this pathogen from the pathway.

No record found. No


153




Mycosphaerella tassiana (De Notaris) Johanson [Syn.: Cladosporium cladosporioides (Fresenius) G.A. de Vries] Rot


No

Myrothecium roridum Tode Blight

Yes – Typically a saprophyte. Sporodochia form on the underground parts of some plant hosts, particularly following damage caused by nematodes (Brooks 1945). Reported on taro in the Solomon Islands (McKenzie and Jackson 1986).

Yes. Recorded in Qld (Shivas and Alcorn 1996) and SA (Cook and Dube 1989).

No

Nectria haematococca Berkeley & Broome Dry rot

Yes – Has been reported on taro in French Polynesia (Hammes et al. 1989), Papua New Guinea (Muthappa 1987) and the Solomon Islands (McKenzie and Jackson 1986).


No

Neojohnstonia colocasiae (M.B. Ellis) B. Sutton

No – Causes a leaf spot disease of older leaves (Carmichael et al. 2008). Removal of leaves during harvesting should eliminate this pathogen from the pathway.

No record found. No

Nigrospora sphaerica (Saccardo) E.W. Mason (see Khuskia oryziae)

Passalora colocasiae (Höhnel) U.Braun Teleomorph: Mycosphaerella alocasiae, q.v. [Syn.: Cercospora colocasiae (Höhnel) Chupp;] Taro leaf spot

No – See also Mycosphaerella alocasiae (teleomorph). Rare on older leaves, but removal of leaves at harvest should eliminate this pathogen from the pathway.

No record found. No


154




Phyllosticta colocasiae Höhnel Teleomorph: Asteromella spermatial state of Mycosphaerella alocasia H & P Sydow (van der Aa & Vanev 2002) Synonym: Cercospora colocasiae (Höhnel) Chupp Shot hole

No – Affects older taro leaves, causing a brown leaf spot, but does not cause significant damage (Hunter and Shafia 2000). Removal of leaves during harvest should remove Phyllosticta colocasiae from the pathway.

No record found. No

Phyllosticta colocasiicola Höhnel Leaf spot

No – Affects older taro leaves, causing a reddish-brown leaf spot, but does not cause significant damage (Hunter and Shafia 2000). Removal of leaves during harvest should remove Phyllosticta colocasiicola from the pathway.

No record found. No

Phyllosticta colocasiophila Weedon Phyllosticta leaf spot

Yes. Recorded on taro in Qld, but considered a minor disease of low importance (Midmore et al. 2005).

No

Pithomyces chartarum (Berk. & M.A. Curtis) M.B. Ellis


Yes. Recoded in Tas. (Sampson and Walker 1982) and Vic. (Janes 1962).

No

Pseudocercospora colocasiae Deighton Leaf blotch

No – Causes a leaf spot disease of older leaves, but has very little economic impact (Carmichael et al. 2008). Removal of leaves during harvesting should eliminate this pathogen from the pathway.

No record found. No

Rhizopus stolonifer Saccardo Rhizopus rot


No


155




Rosellinia pepo Patouillard Anamorph: Dematophora sp. Black root rot

Yes – Taro is a minor host of this fungus, and the roots, corms and stem base may be infected. However, the roots and stem base are quickly surrounded by a mat of dark hyphae, and external mycelium is visible to the naked eye (CABI 2011). It is likely that most infected taro corms would be removed from the pathway during harvesting or pre-export processing.

No record found. Yes – Rosellinia pepo is plurivorous and many woody and sub-woody crops have been affected throughout its range (Oliviera et al. 2008).

Yes – Economic losses to coffee and cocoa have been reported (Oliviera et al. 2008).

Yes

Sclerotium rolfsii Saccardo Teleomorph: Athelia rolfsii (Curzi) Tu & Kimbrough [Syn.: Pellicularia rolfsii Curzi & West] Sclerotium rot

Yes – Soilborne pathogen that can infect roots and corms, particularly if plant tissues have been attacked by nematodes or arthropod pests (CABI 2011).

Yes. Recorded in NSW (Letham 1995), NT, Qld (Simmonds 1966), SA (Cook and Dube 1989), Tas. (Sampson and Walker 1982) and WA (Shivas 1989).

No

Thanatephorus cucumeris (A.B. Frank) Donk

Yes – Soil pathogen that may be present on roots and corms (CABI 2011).


No

Trichoderma harzianum Rifai Yes. Recorded in NSW (Letham 1995; Wong et al. 2002).

No

Trichoderma koningii Oudemans Yes. Recorded in NSW (Wong et al. 2002).

No

VIRUSES

badnavirus sp. (not yet defined to species level) [Caulimoviridae: Badnavirus]

Yes - The virus may infect systemically and may enter Australia in an infected corm.

No record found (R. Harding pers comm. 2009). No tests for this species have been done using Australian plant samples.

No – The existence of a transmissible virus has not yet been shown (Yang et al. 2003).

No – No disease symptoms have been associated with the virus (Yang et al. 2003).

No


156




colocasia bobone disease virus (CBDV) [Rhabdoviridae not yet defined to genus level]

Yes – The virus infects systemically, and can persist in corms (Zettler et al. 1989). It may enter Australia in an infected corm or vectored by taro planthoppers present in the petioles.

No record found. Yes – CBDV could become established if a volunteer taro plant grows from an infected corm. CBDV is transmitted by delphacid planthoppers, probably including Tarophagus persephone and Tarophagus colocasiae, which occur in Queensland and the Northern Territory (Zettler et al. 1989; Matthews 2003; AICN 2011; CABI 2011).

Yes – This virus causes bobone disease that leads to crop losses that have been estimated to be 25 percent (Gollifer et al. 1978; Jackson 1978). The virus probably also causes alomae disease when co-infecting with another virus. Alomae disease kills taro plants and may wipe out taro crops (Gollifer et al. 1978; Shaw et al. 1979).

Yes

Dasheen mosaic virus (DsMV) [Potyviridae: Potyvirus]

Yes – Virus can be transmitted through use of infected planting materials (Carmichael et al. 2008), so is likely to be systemic.

Yes. Recorded in Qld (Greber and Shaw 1986). Found in coastal regions in NSW, Qld and Vic., and nationwide throughout urban regions on house plants (Greber 1987).

No

French Polynesian strain of Dasheen mosaic virus (FP-DsMV) [Potyviridae: Potyvirus]

Yes – FP-DsMV infects systemically. It has been found in most taro plant parts including corm tissue (Hu et al. 1995) and is probably spread when corms are planted (Simone and Zettler 2009). It may enter Australia in an infected corm.

No record found. Yes – FP-DsMV may become established if a volunteer taro plant grows from an infected corm. FP-DsMV is transmitted by aphids, including Myzus persiicae, Aphis craccivora and Aphis gossypii, all of which are present in Australia (Simone and Zettler 2009; Carmichael et al. 2008; AICN 2011).

Yes – The ordinary strain of DsMV may be asymptomatic or cause minimal damage (Revill et al. 2005a). However, the French Polynesian strain is reported to cause severe disease and plants may fail to recover (Carmichael et al. 2008; McCormack 2007).

Yes

Konjac mosaic virus (KMV) [Syn. Zantedeschia mosaic virus] [Potyviridae: potyvirus]

Yes – The virus is known to systemically infect other aroid species and may enter Australia in an infected taro corm.

No record found. Yes – KMV may become established if a volunteer taro plant grows from an infected corm. KMV is transmitted by aphids, including Aphis gossypii, which is present in Australia (Brunt et al. 1996; AICN 2011)

No – Zantedeschia mosaic virus (syn. Konjac mosaic virus) has been recorded on an unnamed Colocasia sp. in India (GenBank accession code EU979524.1). No record of disease on Colocasia sp. has been found.

No


157




Taro bacilliform virus (TaBV) [Caulimoviridae: Badnavirus]

Yes. Recorded in Qld (Midmore et al. 2006; Carmichael et al. 2008). Intercepted once on Cyrtosperma johnstonii imported from Solomon Islands (Jones et al. 1980).

No

taro reovirus (TaRV) [Reoviridae not yet defined to genus level]

Yes – The virus infects systemically (Pearson et al. 1999; Revill 2005b) and may enter Australia in an infected corm.

No record (Revill et al. 2005a; R. Harding pers comm. 2009).

Yes – Little is known about TaRV (Revill et al. 2005b). TaRV may become established if a volunteer taro plant grows from an infected corm. By analogy with other plant-infecting reoviruses, it is likely to be transmitted by an insect vector (Fauquet et al. 2005).

Yes – When co-infecting with CBDV, TaRV may cause alomae disease that destroys crops (Revill et al. 2005b), although the etiology of alomae disease is unclear. The virus has not been unequivocally linked with symptoms (Revill et al. 2005b).

Yes

Taro vein chlorosis virus (TaVCV) [Rhabdoviridae: Nucleorhabdovirus]

Yes – Symptoms expressed in the leaves, and transmission is thought to be by sap feeding leafhoppers (Tarophagus spp.) (QUT 2003). No definitive data on whether corms can carry the virus, but as the virus is sap borne it is assumed that this is so.

No record found. Yes – TaVCV could become established if a volunteer taro plant grows from an infected corm. It is not known how TaVCV is transmitted, but it is suspected Tarophagus proserpina and related planthoppers have this role (QUT 2003). Tarophagus proserpina has been reclassified into three species two of which exist in Australia (QUT 2003; CABI 2011).

Yes – TaVCV causes chlorosis, malformation and sometimes leads to necrosis (Revill 2005a). When co-infecting with CBDV, TaVCV might contribute to alomae disease (Revill et al. 2005a; Carmichael et al. 2008), although the etiology of alomae disease is uncertain.

Yes

tomato zonate spot virus (TZSV) [Bunyaviridae: Tospovirus]

Yes – Taro plants can be infected (Dong et al. 2008). No definitive data on whether corms can carry the virus, but as the virus is sap borne it is assumed that this is so.

No record found. Yes – TZSV could become established if a volunteer taro plant grows from an infected corm. Tospoviruses are vectored by thrips species known to be present in Australia. TZSV has a wide host range (Dong et al. 2008).

Yes – TZSV infection results in necrotic lesions of leaves and ringspots on fruit. Reported to have devastating effects on crops. TZSV affects a number of agricultural crops and ornamental plants including tomato, chilli, spinach, taro and carnations (Dong et al. 2008).

Yes

Review of import conditions for fresh taro corms Appendix B

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Appendix B: Additional data for quarantine pests

Quarantine pest Elytroteinus subtruncatus (Fairmaîre, 1881)

Synonyms Pteroporus subtruncatus Fairmaîre, 1881

Common name(s) Fiji ginger weevil, Fiji lemon weevil

Main hosts Colocasia esculenta (Follett et al. 2007; Mau and Martin Kessing 1992a), Citrus limon, Cordyline terminalis, Cycas spp., Hedychium coronarium, Hemerocallis sp., Marattia douglasii, Persea americana, Saccharum officinarum, Strelitzia reginae (Mau and Martin Kessing 1992a; Follett et al. 2007), Ipomoea batatas (not confirmed) (Shea 2004), Dioscorea spp. (Wilson 1987), Piper methysticum (Fakalata 1981), Begonia spp. (Simmonds 1928; Simmonds 1932) and Zingiber officinale (Ecoport 2011).

The common name refers to its discovery on the ornamental ginger Hedychium coronarium in Hawaii. It has also been reported on Zingiber officinale in Tonga (Ecoport 2011).

Distribution Cook Islands, Fiji, Niue, Samoa, Tonga (CABI 2011), Hawaii, French Polynesia (Nishida 2008).

Mau and Martin Kessing (1992a) recorded this species for New Zealand, apparently in error. The species is listed as a Regulated Pest for New Zealand, with interceptions subject to treatment, re-export or destruction (NZ MAF 2002). May (1993) does not consider it as being present in New Zealand. Miller (1923) recorded an interception on lemons entering New Zealand from Fiji.

Quarantine pests

Eucopidocaulus tridentipes (Arrow, 1911)

Papuana biroi (Endrödi, 1969)

Papuana cheesmanae Arrow, 1941

Papuana huebneri Fairmaire, 1879

Papuana inermis Prell, 1912

Papuana japenensis Arrow, 1941

Papuana laevipennis Arrow, 1911

Papuana semistriata Arrow, 1911

Papuana szentivanyi (Endrödi, 1971)

Papuana trinodosa Prell, 1912

Papuana uninodis Prell, 1912

Synonyms Eucopidocaulus tridentipes = Papuana tridentipes

Papuana laevipennis = P. woodlarkiana subsp. laevipennis

Papuana semistriata = P. woodlarkiana subsp. semistriata

Common name(s) Taro beetle, Bintang bilong taro (PNG), Taro bitol (PNG), Dalo bitol (Fiji)

Main hosts The larvae feed in organic detritus at the base of numerous plants, including the grasses Sorghum verticilliflorum, Pennisetum purpureum, Imperata cylindrica and Phragmites karka (Onwueme 1999). The beetles feed on many other hosts. Primary hosts for the adult beetle include: Alocasia spp., Amorphophallus spp., Angiopteris spp., Brassica spp., Colocasia spp., Cyrtosperma spp., Marattia spp., Musa spp. and Xanthosoma saggitifolia.

Secondary hosts include Ananas comosus, Areca catechu, Arachis hypogaea, Camellia


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sinensis, Cocos nucifera, Coffea arabica, Commelina spp., Crinum spp., Dioscorea alata, Dioscorea rotundata, Elaeis guineensis, Ipomea batatas, Pandanus spp., Saccharum officinarum, Solanum tuberosum and Theobroma cacao (Masamdu and Simbiken 2000).

Distribution About nineteen species of taro beetle are known, 18 in the genus Papuana and 1 in the genus Eucopidocaulus. The beetles are native to the Indo-Pacific region, with 14–18 or more species found in Papua New Guinea, 12–18 in the Solomon Islands, five in Vanuatu, and one each in Fiji, Kiribati and New Caledonia (Onwueme 1999; SPC 2003). Six species are endemic to PNG, four to Solomon Islands and two to Vanuatu (Adams 2006a). About eleven or twelve species are serious pests of taro in the South Pacific region.

Distribution of the beetles, by species, includes the following (list not exhaustive):

Eucopidocaulus tridentipes: Papua New Guinea

Papuana biroi: Papua New Guinea

Papuana cheesmanae: Papua New Guinea, Vanuatu

Papuana huebneri: Fiji, Kiribati, New Caledonia, Papua New Guinea, Solomon Islands, Vanuatu

Papuana inermis: Solomon Islands, Vanuatu

Papuana japenensis: Papua New Guinea

Papuana laevipennis: Papua New Guinea, Solomon Islands

Papuana semistriata: Papua New Guinea

Papuana szentivanyi: Papua New Guinea

Papuana trinodosa: Papua New Guinea

Papuana uninodis: Fiji, Solomon Islands, Vanuatu

The presence of these beetles in Australia is uncertain. Four specimens of Papuana sp. were collected from the Iron Range on Cape York Peninsula, Queensland in 1968 (APPD 2009). Brooks (1965) identified a population of Papuana woodlarkiana in far north Queensland.

Quarantine pest Tarophagus proserpina (Kirkaldy, 1907)

Synonyms Megamelus proserpina Kirkaldy, 1907

Common name(s) Taro planthopper

Main hosts Colocasia esculenta (Matthews 2003) is the main host, but occasionally reported on Alocasia and Cyrtospermum species (CABI 2011; Carmichael et al. 2008).

Distribution American Samoa, Cook Islands, Fiji, French Polynesia, New Caledonia, Niue, Papua New Guinea, Samoa, Tonga, Tuvalu, Vanuatu, Samoa, Wallis and Futuna (Matthews 2003; CABI 2011).


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Quarantine pest Aspidiella hartii (Cockerell, 1895)

Synonyms Aspidiotus hartii Cockerell, 1895

Common name(s) Yam scale

Main hosts Has been reported on hosts from at least seven plant families. Known hosts include Colocasia esculenta, Curcuma longa, Cyperus odoratus, Dioscorea alata, Ipomoea batatas, Portulaca oleracea, Tripsacum laxum and Zingiber officinale (Ben-Dov et al. 2011).

Distribution Dominican Republic, Federated States of Micronesia, Fiji, Guadeloupe, Haiti, India, Ivory Coast, Martinique, Mauritius, New Caledonia, Papua New Guinea, Philippines, Puerto Rico, Saint Croix, Sierra Leone, Solomon Islands, Tonga, Trinidad and Tobago, U.S. Virgin Islands, Vanuatu (Ben-Dov et al. 2011).

Quarantine pests Paraputo aracearum Williams, 2005 Paraputo leveri (Green, 1934)

Synonyms Paraputo leveri: Pseudococcus leveri Green, 1934; Cataenococcus leveri (Green)

Common name(s) Paraputo mealybugs

Main hosts Colocasia esculenta (Ecoport 2011), Cocos nucifera, Coffea robusta, Ficus (Svent-Ivany 1960), Balanophora, Bischofia javanica, Coffea arabica, Coffea canephora, Ficus septica, Inocarpus edulis, Mangifera indica, Syzygium aromaticum, Vitis vinifera (Ben-Dov 1994; Ben-Dov et al. 2011).

Distribution Paraputo aracearum: Fiji (Williams 2005).

Paraputo leveri: American Samoa, Federated States of Micronesia, Fiji, Indonesia, Malaysia, Papua New Guinea, Niue, Solomon Islands, Thailand, Tonga, Vanuatu, Samoa (Szent-Ivany and Catley 1960; Ben-Dov 1994; Ecoport 2011; Ben-Dov et al. 2011).

Quarantine pest Patchiella reaumuri (Kaltenbach, 1843)

Synonyms

Common name(s) Taro root aphid

Main hosts Colocasia esculenta (Sato and Hara 1997); Arum spp., Tilia spp. (Macfarlane 1999; Carmichael et al. 2008).

Distribution Present in unspecified European countries (Macfarlane 1999; Carmichael et al. 2008), as well as Hawaii (Sato and Hara 1997) and the Solomon Islands (Ecoport 2011).

The insect has been known on upland taro on the Hawaiian island of Hawaii since 1971. It was subsequently found on Oahu in 1995. An infestation on Lanai in 1994 was eradicated (Sato and Hara 1997).


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Quarantine pests Helicotylenchus microcephalus Sher, 1966

Helicotylenchus mucronatus Siddiqi, 1963

Synonyms Helicotylenchus microcephalus Sher = Helicotylenchus belurensis Sigh & Khera

Common name(s) Spiral nematodes

Main hosts Helicotylenchus microcephalus:

Abelmoschus esculentus, Aleurites moluccana, Alocasia macrorrhizos, Anacardium occidentale, Ananas comosus, Annona muricata, Arachis hypogaea, Araucaria heterophylla, Asparagus setaceus, Bixa orellana, Brachiaria brizantha, Brachiaria miliifolius, Brachiaria ruziziensis, Brassica chinensis, Brassica oleracea, Broussonetia papyrifera, Brugmansia x candida, Cajanus cajun, Calophyllum inophyllum, Camellia sinensis, Capsicum annum, Capsicum frutescens, Carica papaya, Casuarina equisetifolia, Ceiba pentandra, Cenchrus ciliaris, Chloris gayana, Citrullus lanatus, Citrus aurantifolia, Citrus limon, Cocos nucifera, Coffea sp., Colocasia esculenta, Croix lachryma-jobi, Crotalaria pallida, Daucus carota, Delonix regia, Desmodium intortum, Digitaria eriantha, Dioscorea alata, Dioscorea esculentum, Erythrina subumbrans, Glycine max, Hibiscus schizopetalus, Hibiscus tiliaceus, Inocarpus fagifer, Ipomaea batatas, Ipomoea pes-caprae, Jatropha curcas, Lactuca sativa, Leucaena leucocephala, Lycopersicon esculenta, Macadamia tetraphylla, Mangifera indica, Manihot esculenta, Mentha arvensis, Mimosa pudica, Miscanthuis floridulus, Musa sapientum, Pandanus sp., Panicum maximum, Panicum spectabile, Parinari glaberrima, Paspalum coryphaeum, Phaeomeria speciosa, Phaseolus vulgaris, Phoenix dactylifera, Pinus massoniana, Psophocarpus tetragonolobus, Raphinus sativus, Ravenala madagascariensis, Ricinus communis, Saccharum edule, Saccharum officinarum, Setaria palmifolia, Setaria sphacelata, Solanum melongena, Sorghum bicolor, Sorghum halepense, Spondias dulcis, Tamarindus indica, Tectona grandis, Terminalia catappa, Theobroma cacao, Trichosanthes cucumerina, Vigna radiata, Xanthosoma sagittifolium, Xanthosoma violaceum, Zea mays (Ecoport 2011); also Cynodon dactylon and Thymelea hirsuta (Ibrahim et al. 2000).

Helicotylenchus mucronatus:

Abelmoschus manihot, Aleurites moluccana, Allium cepa, Allium sp., Alocasia macrorrhizos, Alphitonia zizyphoides, Ananas comosus, Annona muricate, Arachis hypogaea, Bambusa vulgaris, Bauhinia monandra, Brassica sp., Broussonetia papyrifera, Cananga odorata, Capsicum frutescens, Carica papaya, Ceiba pentandra, Citrullus lanatus, Citrus limon, Citrus sinensis, Cocos nucifera, Codiaeum variegatum, Colocasia esculenta, Cordyline fruticose, Cucumis sativus, Cucumis sp., Cucurbita maxima, Cucurbita sp., Cyathea sp., Dioscorea alata, Dioscorea bulbifera, Dioscorea esculenta, Dioscorea nummularia, Dysoxylum forsteri, Elettaria cardamomum, Endospermum macrophyllum, Ficus tinctorial, Glochidion ramiflorum, Gmelina arborea, Grevillea banksii, Heliconia indica, Hibiscus tiliaceus, Inocarpus fagifer, Ipomoea batatas, Kleinhofia hospita, Lantana camara, Lycopersicon esculentum, Macadamia tetraphylla, Macaranga seemannii var. seemannii, Mangifera indica, Manihot esculenta, Miscanthus floridulus, Morinda citrifolia, Musa sapientum, Myristica inutilis, Nicotiana tabacum, Oryza sativa, Passiflora edulis, Persea americana, Piper methysticum, Piper puberulum, Pometia pinnata, Psidium guajava, Rhus taitensis, Saccharum edule, Saccharum officinarum, Sechium edule, Setaria palmifolia, Solanum tuberosum, Swietenia macrophylla, Syzygium richii, Tacca leontopetaloides, Tectona grandis, Theobroma cacao, Urena lobata, Vigna radiata, Xanthosoma sagittifolium, Zea mays, Zingiber officinale, Zingiber zerumbet (Ecoport 2011).

Distribution Helicotylenchus microcephalus:

Asia: India (Lal and Khan 1993), Iran (Hashemi and Kheyri 2003), Jordan (Hashim 1983), Oman (Waller and Bridge 1978), Pakistan (Zarina 2006), Thailand (Ratanaprapa and Boonduang 1975).


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Africa: Egypt (Ibrahim et al. 2000), Kenya (Njuguna and Bridge 1998), Mozambique (Ecoport 2011), Nigeria (Badra and Caveness 1985), South Africa (NZ MAF 1999; Marais and Buckley 1992), Sudan (Zeidan and Geraert 1990).

North America: USA (Lehman 2002).

Central America: Cuba (Schliephake 1985), Guadeloupe (Marais et al. 1999).

South America: Brazil (Rossi and Ferraz 2005), Venezuela (Maggiorani et al. 2004).

Oceania: Fiji, Papua New Guinea, Tonga, Samoa (Ecoport 2011).

Helicotylenchus mucronatus:

Asia: India (Mishra and Mandal 1989; Rama and Dasgupta 2000).

Africa: Cameroon (Ali and Geraert 1975), Kenya (Waudo et al. 1998).

Central America: Guadeloupe (Marais et al. 1999; Queneherve and Berg 2005).

Oceania: American Samoa, Fiji , Niue, Papua New Guinea, Solomon Islands, Tonga (Ecoport 2011), Samoa (Bridge 1988).

Quarantine pest Hirschmanniella miticausa Bridge, Mortimer & Jackson, 1983

Synonyms

Common name(s) Taro nematode

Main hosts Colocasia esculenta (Bridge 1988)

Distribution Papua New Guinea, Solomon Islands.

Other Hirschmanniella species have been noted as associated with taro in Taiwan (Bridge 1988; Jatala and Bridge 1990; CABI 2011), but seem to cause little damage. Hirschmanniella miticausa is listed as a quarantine pest for Taiwan (Plant Nematode Lab Taiwan 2003a), while ‘Hirschmanniella sp.’ is listed as a major nematode pest of the stem vegetables Zinania latifolia and Nelumbo nucifera, but not of taro (Plant Nematode Lab Taiwan 2003b).

Quarantine pest Longidorus sylphus Thorne, 1939

Synonyms This species is sometimes included in the broadly defined Longidorus elongatus (de Man, 1876) complex.

Konicek (1961) and Konicek and Jensen (1961) renamed the nematode that attacks peppermint crops in the USA, until then known as Longidorus sylphus, as Longidorus menthasolanus. They provided characters that distinguished their species from Longidorus sylphus and Longidorus elongatus. However, their name seems to have had little use, and Siddiqi (1962) included Longidorus menthasolanus in Longidorus elongatus. Hooper (1961) quoted in Robbins and Brown (1995), provided distinguishing characters for Longidorus sylphus and Longidorus elongatus. Whitehead (1998) considered that Longidorus sylphus (at least in the context of North American Mentha crops) was synonymous with Longidorus elongatus.

Most other authors maintain Longidorus sylphus and Longidorus elongatus as distinct species (Polinkovskii 1979; Green and Skotland 1993; Ooka 1994; Ferris 1999). CABI (2011) treats Longidorus menthasolanus as a synonym of Longidorus elongatus, but keeps Longidorus sylphus distinct. This taxonomic confusion, however, means that records of geographical and host status for Longidorus sylphus are equally confused.

A number of records of ‘Longidorus sp.’ are known from widely scattered parts of Australia, including the Northern Territory, New South Wales, Victoria and Tasmania (APPD 2009), but without species level identification it is impossible to tell whether


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these might represent this species. McLeod et al. (1994) recorded Longidorus taniwha on a range of native Australian taxa in South Australia, and Longidorus sp. on apple, pear and peach in Sydney.

Common name(s) Needle nematode, mint nematode

Main hosts The host data cited below is for nematodes identified by the authors in each case as ‘Longidorus sylphus’. If this species is considered synonymous with Longidorus elongatus, then the host list is much wider, and includes turf grasses, root vegetables such as beetroot and carrot, and fruit trees. Even some of the hosts below may be more correctly attributed to Longidorus elongatus s. str. rather than Longidorus sylphus.

Hosts include Colocasia esculenta (Ooka 1994), Amygdalus nana, Amygdalus communis, Cydonia oblonga, Juglans regia, Malus domesticus, Prunus mahaleb, Pyrus sativa (Katalan-Gateva 1980), Fragaria sp. (Baker 1959; Townshend 1962), Mentha spp. (Konicek 1961), Rosa damascena (Choleva et al. 1980), Saccharum officinarum (Allow and Katcho 1967) and Vitis vinifera (Polinkovskii 1979; Ferris 1999).

Distribution The distribution data cited below is for nematodes identified by the authors in each case as ‘Longidorus sylphus’. If this species is considered synonymous with Longidorus elongatus, then the distribution is much wider, and includes an old record for South Australia (on Lolium, McLeod et al. (1994)), much of Europe, central Asia, and New Zealand (CABI 2011). There is considerable doubt about the true distribution of Longidorus elongatus, and some of the records for that species may belong with Longidorus sylphus or other segregate species.

Asia: Iraq (Allow and Katcho 1967; Katcho and Allow 1969) Africa: Sudan (El-Tigani et al. 1970)

Europe: Belarus, Bulgaria, Moldova Rep. (Fauna Europaea 2009)

North America: Canada (Baker 1959; Townshend 1962), USA (Lehman 2002)

Oceania: Hawaii (Ooka 1994)

Quarantine pest Xanthomonas axonopodis pv. dieffenbachiae (McCulloch & Pirone, 1939) Vauterin et al., 1995

Synonyms Xanthomonas campestris pv. dieffenbachiae (McCulloch & Pirone) Dye

Xanthomonas campestris pv. aracearum (Berniac, 1974) Dye, 1978

Xanthomonas campestris pv. syngonii Dickey & Zumoff, 1987

Xanthomonas dieffenbachiae (McCulloch & Pirone) Dowson, 1943

Bacterium dieffenbachiae McCulloch & Pirone, 1939

Phytomonas dieffenbachiae McCulloch & Pirone, 1939

Common name(s) Bacterial blight

Main hosts Colocasia esculenta, Aglaonema spp., Anthurium spp., Colocasia spp., Dieffenbachia spp., Epiprenum spp., Philodendron spp., Syngonium spp., Xanthosoma spp. (Phookan et al. 1996; Chase et al. 1992)

Distribution Asia: India (Phookan et al. 1996)

Central America: Costa Rica (Laguna et al. 1983)

Oceania: Papua New Guinea (Tomlinson 1987), Hawaii (Chase et al. 1992)


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Quarantine pest Corallomycetella repens (Berkeley & Broome) Rossman & Samuels

Anamorph: Rhizostilbella hibisci (Patouillard) Seifert

Synonyms Teleomorph: Sphaerostilbe repens Berkeley & Broome, Stilbum incarnatum Junghuhn; Corallomyces elegans Berkeley & M.A. Curtis, J.; Corallomycetella heinsenii Hennings; Corallomyces mauritiicola Hennings; Nectria mauritiicola (Hennings) Seifert & Samuels; Corallomyces berolinensis Hennings; Nectria coccinea var. platyspora Rehm; Nectria platyspora (Rehm) Weese.

Anamorph: Stilbum hibisci Patouillard; Rhizostilbella rubra van der Wolk; Stilbum incarnatum Wakker; Cephalosporium kashiense R.Y.Roy & G.N.Singh; Acremonium kashiensis (R.Y.Roy & G.N.Singh) W.Gams.

Common name(s) Corallomycetella root rot

Main hosts Colocasia esculenta, Theobroma cacao, Hevea brasiliensis (Ecoport 2011), Aleurites montana, Cajanus cajun, Camellia sinensis, Carica papaya, Caryota urens, Cassia sp., Citrus aurantifolia, Citrus grandis, Citrus medica, Citrus sinensis, Elaeis guineensis, Erythrina sp., Ficus carica, Gliricidia sepium, Manihot esculenta, Manihot utilissima, Mauritia flexuosa, Metroxylon vitiense, Nelumbium nelumbo, Nymphaea sp., Pachyrhizus erosus, Persea americana, Pueraria sp., Sterium fasciatum, Tectona grandis, Trapa bicornis, Zingiber officinale (Farr and Rossman 2011), Artocarpus integrifolia, Coffea sp., Dioscorea sp., Hibiscus sp., Mangifera indica, Maranta arundinacea, Musa sapientum, Voandzeia subterranea (Mycobank 2011).

Distribution Asia: India, Indonesia, Malaysia, Myanmar, Sri Lanka, Thailand (CMI 1968), Hong Kong, Singapore, Solomon Islands (Mycobank 2011), Japan (JSCC 2009)

Africa: Cameroon, Central African Republic, Congo, Gabon, Ghana, Cote d'Ivoire, Mauritius, Nigeria, Senegal, Sierra Leone, Uganda (CMI 1968)

North America: Bermuda (CMI 1968), USA (Farr and Rossman 2011)

Central America: Costa Rica, Dominican Republic, Honduras, Jamaica, Puerto Rico, Trinidad and Tobago, Windward and Leeward Islands (CMI 1968)

South America: Colombia, Guyana (CMI 1968), Brazil (Farr and Rossman 2011), Venezuela (Cybertruffle 2007), Surinam (Mycobank 2011)

Oceania: Fiji, New Caledonia, Papua New Guinea (CMI 1968), French Polynesia (Ecoport 2011), New Zealand (Landcare Research 2009), Fiji (Farr and Rossman 2011)

Rossman et al. (1999) cited a syntype from a greenhouse in Germany.

This species has been claimed to be present in Australia, as a mycorrhizal symbiont of the introduced weedy orchid Disa bracteata, which is spreading in southern Australia (southwestern Western Australia, South Australia, Victoria) (Bonnardeaux et al. 2007). Disa bracteata is native to South Africa. Nectria mauritiicola was identified on molecular evidence (ITS sequencing) from an orchid accession from southern Western Australia, identified as a 99 percent match to a GenBank sequence from Russia (Bonnardeaux et al. 2007). This is the only record of the pathogen from Australia. It is not recorded from South Africa, and no other records of it from Russia have been traced. This record seems doubtful for a pathogen of waterlogged tropical soils.


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Quarantine pest Marasmiellus colocasiae Capelari & Antonín

Synonyms

Common name(s) Corm rot

Main hosts Colocasia esculenta (Capelari et al. 2010).

Distribution Has only been reported from Brazil (Capelari et al. 2010).

Quarantine pest Rosellinia pepo Patouillard

Synonyms

Common name(s) Black root rot

Main hosts Coffea spp., Theobroma cacao, Cajanus cajan, Camellia sinensis, Citrus aurantifolia, Erythrina spp., Hevea brasiliensis, Garcinia mangostan, Inga spp., Manihot esculenta, Myristica fragans, Persea americana, Piper nigrum, Syzygium aromaticum, Theobroma grandiflorum, Xanthosoma spp. (Oliveira et al. 2008), Colocasia esculenta (CABI 2011)

Distribution Present in tropical areas of Central and South America, the West Indies, West Africa and Asia (Oliveira et al. 2008).

Central America: Cuba, Dominica, Dominican Republic, El Salvador, Granada, Guadeloupe, Martinique, Puerto Rico, Saint Lucia, Trinidad and Tobago

South America: Brazil, Colombia, French Guiana, Surinam, Venezuela (CABI 2011)

Quarantine pest Phytophthora colocasiae Raciborski

Synonyms Kawakamia colocasiae (Raciborski) Sawada; Phytophthora parasitica var. colocasiae (Raciborski) Sarej

Common name(s) Taro leaf blight; Blight of dasheen; Phytophthora leaf blight; Taro corm rot; Leaf blight of Gabi; flétrissure des feuilles de taro (French); Yu yi ping (Chinese)

Main hosts Alocasia macrorrhiza (Brooks 2006; Erwin and Ribeiro 1996), Amorphophallus campanulatus (= Amorphophallus paeoniifolius) (Erwin and Ribeiro 1996; Farr and Rossman 2011), Catharanthus roseus, Colocasia antiquorum, Colocasia esculenta (Brooks 2006), Colocasia esculenta var. globulifera, Dracontium polyphyllum (Farr and Rossman 2011), Hevea brasiliensi, Panax quinquefolius, Piper betle, Vinca rosea, Xanthosoma mafaffa, Xanthosoma violaceum Schott (Erwin and Ribeiro 1996), Xanthosoma sagittifolium (Farr and Rossman 2011; Erwin and Ribeiro 1996), Bougainvillea spectabilis (CABI 2011).

Distribution Asia: Bangladesh, Brunei Darussalam, China, Taiwan, India, Indonesia, Japan, Malaysia, Myanmar, Nepal, Pakistan, Philippines, Sri Lanka, Thailand

Africa: Cameroon, Equatorial Guinea, Ethiopia, Seychelles

North America: USA

Central America: Dominican Republic

South America: Argentina

Oceania: American Samoa, Federated States of Micronesia, Guam, Hawaii, Northern Mariana Islands, Palau, Papua New Guinea, Samoa and Solomon Islands (CABI 2011)


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Quarantine pest Phytophthora sp.

Synonyms

Common name(s) Taro pocket rot

Main hosts Colocasia esculenta (Uchida 1998; CTAHR 2002)

Distribution Only confirmed for Hawaii (Uchida 1998). The disease may be more widespread in the Pacific (Uchida et al. 2003) but this is not yet proven, as other pathogens cause similar damage (Uchida 1998).

Quarantine pests Pythium carolinianum V.D.Matthews

Synonyms

Common name(s) Pythium corm rot, Corm and root rot, Soft rot, Corm soft rot

Main hosts Colocasia esculenta, Acorus calamus, Lathyrus palustris, Myriophyllum aquaticum, Myriophyllum brasiliense, Potamogeton crispus, Rorippa amphibian, Rumex aquaticus (Farr and Rossman 2011), Gossypium hirsutum (Abdelzaher and Elnaghy 1998), Agrotis palustris (Abad et al. 1994)

Distribution China (Su et al. 2001), Egypt (Abdelzaher and Elnaghy 1998), Hawaii (Ooka 1994), Papua New Guinea, Poland (CABI 2011), USA (Abad et al. 1994)

Quarantine pest colocasia bobone disease virus (CBDV)

Synonyms taro large bacilliform virus

Common name(s)

Main hosts Colocasia esculenta (Carmichael et al. 2008), Philodendron selloum (in laboratory inoculation tests) (Zettler et al. 1989)

Distribution Papua New Guinea (Shaw et al. 1979), Solomon Islands (Jackson 1980)

Quarantine pest Dasheen mosaic virus (DsMV)

Synonyms

Common name(s)

Main hosts Aglaonema spp., Alocasia spp., Amorphophallus spp., Anthurium spp., Caladium spp., Colocasia spp., Cyrtosperma merkusii, Dieffenbachia spp., Philodendron spp., Spathiphyllum spp., Xanthosoma spp., Zantedeschia spp. (CABI 2011)

Distribution Asia: China, India, Japan, Taiwan

Europe: Belgium, Denmark, Italy, Netherlands, United Kingdom

Africa: Cameroon, Egypt, Nigeria, South Africa

North America: USA

Central America: Costa Rica, Cuba, Dominican Republic, Jamaica, Martinique, Puerto Rico, Trinidad and Tobago


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South America: Brazil, Venezuela

Oceania: American Samoa, Australia, Cook Islands, Federated States of Micronesia, Fiji, French Polynesia, Guam, Hawaii, Kiribati, New Caledonia, New Zealand, Niue, Papua New Guinea, Samoa, Solomon Islands, Tonga, Vanuatu (CABI 2011)

The virus is widespread worldwide, including Australia. However, a particularly virulent strain is known from French Polynesia, confined to that country, and not recorded for Australia.

Quarantine pest taro reovirus (TaRV)

Synonyms

Common name(s)

Main hosts Colocasia esculenta (Devitt et al. 2001; Revill et al. 2005a)

Distribution Papua New Guinea, Solomon Islands, Vanuatu (Revill et al. 2005a; Davis et al. 2005; Davis et al. 2006)

Quarantine pest Taro vein chlorosis virus (TaVCV)

Synonyms Colocasia bobone disease rhabdovirus - Fiji strain; Colocasia vein chlorosis rhabdovirus

Common name(s)

Main hosts Colocasia esculenta (Pearson et al. 1999)

Distribution Federated States of Micronesia, Fiji, New Caledonia, Palau, Papua New Guinea, Philippines, Solomon Islands, Tuvalu, Vanuatu (Pearson et al. 1999; Revill et al. 2005a; Carmichael et al. 2008; Ecoport 2011).

Quarantine pest tomato zonate spot virus (TZSV)

Synonyms

Common name(s)

Main hosts Tomato (Lycopersicum esculentum), chilli (Capsicum annuum), carnation (Dianthus caryophyllus), curly dock (Rumex crispus), spinach (Spinacia oleracea) and taro (Colocasia esculenta) (Dong et al. 2008).

Distribution China (Dong et al. 2008).

Review of import conditions for fresh taro corms Appendix C

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Appendix C: Biosecurity framework

Australia's biosecurity policies The objective of Australia’s biosecurity policies and risk management measures is the prevention or control of the entry, establishment or spread of pests and diseases that could cause significant harm to people, animals, plants and other aspects of the environment.

Australia has diverse native flora and fauna and a large agricultural sector, and is relatively free from the more significant pests and diseases present in other countries. Therefore, successive Australian Governments have maintained a conservative, but not a zero-risk, approach to the management of biosecurity risks. This approach is consistent with the World Trade Organization (WTO) Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement).

The SPS Agreement defines the concept of an ‘appropriate level of protection’ (ALOP) as the level of protection deemed appropriate by a WTO Member establishing a sanitary or phytosanitary measure to protect human, animal or plant life or health within its territory. Among a number of obligations, a WTO Member should take into account the objective of minimising negative trade effects in setting its ALOP.

Like many other countries, Australia expresses its ALOP in qualitative terms. Australia’s ALOP, which reflects community expectations through Australian Government policy, is currently expressed as providing a high level of sanitary and phytosanitary protection, aimed at reducing risk to a very low level, but not to zero.

Consistent with the SPS Agreement, in conducting risk analyses Australia takes into account as relevant economic factors: • the potential damage in terms of loss of production or sales in the event of the entry,

establishment or spread of a pest or disease in the territory of Australia • the costs of control or eradication of a pest or disease • and the relative cost-effectiveness of alternative approaches to limiting risks.

Roles and responsibilities within Australia’s quarantine system Australia protects its human4, animal and plant life or health through a comprehensive quarantine system that covers the quarantine continuum, from pre-border to border and post-border activities.

Pre-border, Australia participates in international standard-setting bodies, undertakes risk analyses, develops offshore quarantine arrangements where appropriate, and engages with our neighbours to counter the spread of exotic pests and diseases.

At the border, Australia screens vessels (including aircraft), people and goods entering the country to detect potential threats to Australian human, animal and plant health.

The Australian Government also undertakes targeted measures at the immediate post-border level within Australia. This includes national co-ordination of emergency responses to pest 4 The Australian Government Department of Health and Ageing is responsible for human health aspects of quarantine.


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and disease incursions. The movement of goods of quarantine concern within Australia’s border is the responsibility of relevant state and territory authorities, which undertake inter- and intra-state quarantine operations that reflect regional differences in pest and disease status, as a part of their wider plant and animal health responsibilities.

Roles and responsibilities within the Department The Australian Government Department of Agriculture, Fisheries and Forestry is responsible for the Australian Government’s animal and plant biosecurity policy development and the establishment of risk management measures. The Secretary of the Department is appointed as the Director of Animal and Plant Quarantine under the Quarantine Act 1908 (the Act).

There are three groups within the Department primarily responsible for biosecurity and quarantine policy development and implementation: • Biosecurity Australia conducts risk analyses, including IRAs, and develops

recommendations for biosecurity policy as well as providing quarantine advice to the Director of Animal and Plant Quarantine and AQIS.

• AQIS develops operational procedures, makes a range of quarantine decisions under the Act (including import permit decisions under delegation from the Director of Animal and Plant Quarantine) and delivers quarantine services.

• Product Integrity, Animal and Plant Health Division (PIAPH) coordinates pest and disease preparedness, emergency responses and liaison on inter- and intra-state quarantine arrangements for the Australian Government, in conjunction with Australia’s state and territory governments.

Roles and responsibilities of other government agencies State and territory governments play a vital role in the quarantine continuum. Biosecurity Australia and PIAPH work in partnership with state and territory governments to address regional differences in pest and disease status and risk within Australia, and develop appropriate sanitary and phytosanitary measures to account for those differences. Australia’s partnership approach to quarantine is supported by a formal Memorandum of Understanding that provides for consultation between the Australian Government and the state and territory governments.

Depending on the nature of the good being imported or proposed for importation, Biosecurity Australia may consult other Australian Government authorities or agencies in developing its recommendations and providing advice.

As well as a Director of Animal and Plant Quarantine, the Act provides for a Director of Human Quarantine. The Australian Government Department of Health and Ageing is responsible for human health aspects of quarantine and Australia’s Chief Medical Officer within that Department holds the position of Director of Human Quarantine. Biosecurity Australia may, where appropriate, consult with that Department on relevant matters that may have implications for human health.

The Act also requires the Director of Animal and Plant Quarantine, before making certain decisions, to request advice from the Environment Minister and to take the advice into account when making those decisions. The Australian Government Department of Sustainability, Environment, Water, Population and Communities (DSEWPC) is responsible


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under the Environment Protection and Biodiversity Conservation Act 1999 for assessing the environmental impact associated with proposals to import live species. Anyone proposing to import such material should contact DSEWPC directly for further information.

When undertaking risk analyses, Biosecurity Australia consults with DSEWPC about environmental issues and may use or refer to DSEWPC’s assessment.

Australian quarantine legislation The Australian quarantine system is supported by Commonwealth, state and territory quarantine laws. Under the Australian Constitution, the Commonwealth Government does not have exclusive power to make laws in relation to quarantine, and as a result, Commonwealth and state quarantine laws can co-exist.

Commonwealth quarantine laws are contained in the Quarantine Act 1908 and subordinate legislation including the Quarantine Regulations 2000, the Quarantine Proclamation 1998, the Quarantine (Cocos Islands) Proclamation 2004 and the Quarantine (Christmas Island) Proclamation 2004.

The quarantine proclamations identify goods that cannot be imported into Australia, the Cocos Islands and Christmas Island unless the Director of Animal and Plant Quarantine or delegate grants an import permit or unless they comply with other conditions specified in the proclamations. Section 70 of the Quarantine Proclamation 1998, section 34 of the Quarantine (Cocos Islands) Proclamation 2004 and section 34 of the Quarantine (Christmas Island) Proclamation 2004 specify the things the Director of Animal and Plant Quarantine must take into account when deciding whether to grant a permit.

In particular, the Director of Animal and Plant Quarantine (or delegate): • must consider the level of quarantine risk if the permit was granted • must consider whether, if the permit was granted, the imposition of conditions would be

necessary to limit the level of quarantine risk to one that is acceptably low • for a permit to import a seed of a plant that was produced by genetic manipulation, must

take into account any risk assessment prepared, and any decision made, in relation to the seed under the Gene Technology Act

• may take into account anything else that he or she knows is relevant.

The level of quarantine risk is defined in section 5D of the Quarantine Act 1908 as follows:

reference in this Act to a level of quarantine risk is a reference to:

(a) the probability of: (i) a disease or pest being introduced, established or spread in Australia, the Cocos

Islands or Christmas Island (ii) the disease or pest causing harm to human beings, animals, plants, other aspects

of the environment, or economic activities (b) the probable extent of the harm.

The Quarantine Regulations 2000 were amended in 2007 to regulate keys steps of the import risk analysis process. The Regulations: • define both a standard and an expanded IRA • identify certain steps, which must be included in each type of IRA


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• specify time limits for certain steps and overall timeframes for the completion of IRAs (up to 24 months for a standard IRA and up to 30 months for an expanded IRA)

• specify publication requirements • make provision for termination of an IRA • allow for a partially completed risk analysis to be completed as an IRA under the

Regulations.

The Regulations are available at www.comlaw.gov.au.

International agreements and standards The process set out in the Import Risk Analysis Handbook 2007 is consistent with Australia’s international obligations under the SPS Agreement. It also takes into account relevant international standards on risk assessment developed under the International Plant Protection Convention (IPPC) and by the World Organisation for Animal Health (OIE).

Australia bases its national risk management measures on international standards where they exist and when they achieve Australia’s ALOP. Otherwise, Australia exercises its right under the SPS Agreement to apply science-based sanitary and phytosanitary measures that are not more trade restrictive than required to achieve Australia’s ALOP.

Notification obligations Under the transparency provisions of the SPS Agreement, WTO Members are required, among other things, to notify other members of proposed sanitary or phytosanitary regulations, or changes to existing regulations, that are not substantially the same as the content of an international standard and that may have a significant effect on trade of other WTO Members.

Risk analysis Within Australia’s quarantine framework, the Australian Government uses risk analyses to assist it in considering the level of quarantine risk that may be associated with the importation or proposed importation of animals, plants or other goods.

In conducting a risk analysis, Biosecurity Australia: • identifies the pests and diseases of quarantine concern that may be carried by the

commodity • assesses the likelihood that an identified pest or disease would enter, establish or spread • assesses the probable extent of the harm that would result.

If the assessed level of quarantine risk exceeds Australia’s ALOP, Biosecurity Australia will consider whether there are any risk management measures that will reduce quarantine risk to achieve the ALOP. If there are no risk management measures that reduce the risk to that level, trade will not be allowed.

Risk analyses may be carried out by Biosecurity Australia’s specialists, but may also involve relevant experts from state and territory agencies, the Commonwealth Scientific and Industrial Research Organisation (CSIRO), universities and industry to access the technical expertise needed for a particular analysis.


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Risk analyses are conducted across a spectrum of scientific complexity and available scientific information. An IRA is a type of risk analysis with key steps regulated under the Quarantine Regulations 2000. Biosecurity Australia’s assessment of risk may also take the form of a non-regulated analysis of existing policy or technical advice to AQIS. Further information on the types of risk analysis is provided in the Import Risk Analysis Handbook 2007.

Review of import conditions for fresh taro corms Appendix D

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Appendix D: History and classification of taro

History of taro cultivation Taro is the English language common name applied to cultivars of the species Colocasia esculenta (L.) Schott (Araceae). Other common names include kachula (Pakistan), sato-imo (Japan), dasheen/eddoe (various Asian and Pacific countries), woo tau (China), gabi (Philippines), dalo (Fiji), arbi/arvi/patra (India), and malanga/malanga islena (Latin America), but there are many more (see Wilson and Siemonsma 1996; Vinning 2003; Ivancic and Lebot 2000).

Taro was one of the earliest cultivated plants, with a cultivation history of at least 10 000 years. The earliest documented record is of transfer from India to Egypt around 2000 years ago (Onwueme 1999). It has also been cultivated in China for at least 2000 years (Onwueme 1999; Xu et al. 2001) and in Malaysia and Africa for a similar period (Onwueme 1999). It is a staple carbohydrate source throughout the Pacific, Asia, and the Caribbean, and widely grown as a minor crop elsewhere. Between 1000 (Kay 1973) and 15 000 (Ivancic and Lebot 2000) cultivars have been recorded, varying in corm size, colour, flavour and texture, in leaf and petiole colour, and time to maturity. Only a relatively small number of these are cultivated commercially.

The origin of taro The place of origin of taro is unclear, with accounts of domestication hampered by lack of good fossil evidence. There are fossil starch grains identified as from Colocasia from Buka (Northern Solomons) from sites dated at 20 000 to 28 000 BP and 9000 BP (Spriggs 2002). Fossil pollen evidence suggests taro was present in the highlands of Papua New Guinea around 8500 years ago. A number of genetic studies have been conducted (Coates et al. 1988; Lebot and Aradhya 1991; Matthews and Terauchi 1994) that suggest that taro originated in the area between India and the Solomon Islands, including New Guinea. Ivancic and Lebot (1999) and Jones and Meehan (1989), on the other hand, suggest an origin in Australia and New Caledonia, perhaps as a descendant of the original Gondwana flora. Such an origin could include that part of New Guinea derived from the Australian continental plate.

Yoshino (2002) suggested taro originated as a diploid species on the southern slopes of the Himalayas, with the development of secondary centres of diversity in the highlands of Yunnan and in Myanmar, followed by dispersal to eastern (China, Japan) and southern (Malaysian peninsula) areas and then to New Guinea and Australia. From this Himalayan area of origin, dispersal also proceeded south to India, then west to northern Africa and the Mediterranean, followed by western Africa and the Caribbean.

Sauer (1993) provided an integrated account of the domestication of taro. He considered that taro was brought into cultivation by the Australoid aborigines of Melanesia at least 6500 years ago in the highland valleys of New Guinea, in a case of independent discovery of cropping. Sauer considered that the Polynesians acquired taro from the Melanesians during Polynesian migration from Asia to Oceania between 1500 and 1000 BC, and that cultivars were traded backwards and forwards across the Pacific during well-documented long-distance voyages up to and including the 12th century. At the same time cultivation of taro spread north into China, being widely grown there by 500 AD. From China it spread to Japan, and the eddoe type was developed in either China or Japan. Taro was recorded in Egypt by 500 BC, being imported


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from India or Arabia, and was found in eastern Africa by mediaeval times, later reaching the Guinea coast. It was transported to the West Indies and the Guianas by the 18th century, as a food source associated with the slave trade.

Kreike et al. (2004) noted that wild type Colocasia esculenta in Indonesia and Papua New Guinea flowered and seeded freely, contrasting with the lack of flowers in cultivars growing in the same countries. They interpreted this as an indication that taro was native to these two countries. Hay (1996) also accepted that Colocasia esculenta was native to Australia and Papua New Guinea, and noted that there are endemic drosophilid flies in Papua New Guinea that are specific to Colocasia esculenta. It should also be noted that the nematode Hirchmanniella miticausa and most of the Papuana group of taro beetles are also native or endemic to the New Guinea/Solomon Islands region, and specifically associated with taro (see Appendix B).

The ancestral type of taro

Conflicting views on the original distribution of taro, and its long history of cultivation, have resulted in different views on which (if any) of the current wild forms correspond with the original species. It has often been assumed that Colocasia esculenta var. antiquorum most closely resembles the ancestral stock, with var. esculenta representing a long-term selection for larger corms. However, Ivancic and Lebot (1999) identified dasheen (var. esculenta) type plants as probably indigenous to New Caledonia. Similar wild plants found in Nepal and Yunnan (China) by Yoshino (2002) were thought to be hybrids arising from interspecific or intergeneric hybridisation within Colocasia or between Colocasia and Alocasia.

Yoshino (2002) suggested that Colocasia esculenta var. aquatilis was probably a descendent of the pre-cultivation species. Vinning (2003) suggested that Colocasia esculenta var. aquatilis should be referred to as ‘wild type’ Colocasia esculenta. Colocasia esculenta is considered native in the Northern Territory of Australia (Cowie and Albrecht 2005), and these stoloniferous plants would be placed in var. aquatilis in an infraspecific classification.

Ivancic and Lebot (2000) considered that there was a ‘true’ wild type (e.g. in the Solomon Islands) characterised by extremely long stolons, fast leaf regeneration, continuous growth, small elongated corms and, usually, high calcium oxalate concentrations. The corms of these plants are almost never eaten, but the leaves may be. In addition these authors recognised wild taro in the Solomon Islands and Papua New Guinea with some characteristics of cultivated types. They also recognised wild taro that they thought may have originated as hybrids between cultivated and true wild type taro, and plants that were obvious and hardly-altered escapes from cultivation.

A study by Kreike et al. (2004) using AFLP DNA fingerprinting techniques found there were two distinct gene pools in diploid taro, one found in the Pacific and Thailand, and the other found only in South East Asia. Two major groups of triploids were found, each internally diverse, suggesting that triploids had arisen at least twice, and that this was an old, rather than recent, event. They found no connection between ploidy and dasheen/eddoe type of corm.

Classification of taro There is no clear consensus on the classification of taro. Names are applied in three main contexts: botanical (taxonomic), agronomic, and cultivar, and there is only limited congruence between the three.


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Formal taxonomic names The formal taxonomy of this group is very complex and the subject of continued scientific debate. The taxonomy of the genus as a whole has not been formally revised for at least 30 years. The standard reference for taxonomic treatment of the group is Purseglove (1972), although Hay (1996) provided a synopsis of Colocasia for Australia and Papua New Guinea, in which he discussed variation within Colocasia esculenta. Traditionally, taxonomists have recognised two main taxa, but there is considerable difference of opinion on the ranks to be applied to them. The two taxa are:

Colocasia esculenta (L.) Schott var. esculenta

Synonyms: Colocasia esculenta var. typica A.F. Hill; Colocasia antiquorum var. esculenta (L.) Schott ex Engl.

This is the plant commonly known as large corm taro, or dasheen type. The variety is characterised by its large cylindrical central corm, lacking hairs, and with few cormels. The central corm provides the main crop.

Colocasia esculenta var. antiquorum (Schott) Hubbard & Rehd

Synonyms: Colocasia antiquorum Schott; Colocasia esculentum subsp. antiquorum Haudricourt; Colocasia esculenta var. globulifera (Engl. & K. Krause) Young; Colocasia antiquorum var. typica Engl.

This is the plant commonly known as small corm taro, or eddoe type. The variety is characterised by having a small, more or less globular, central corm, bearing long shaggy hairs in the upper part, with several relatively large cormels arising laterally. The lateral cormels provide the main crop.

Important works recognising these varieties include Purseglove (1972), Onwueme (1999), Bown (2000), Ivancic and Lebot (2000), Chay-Prove and Goebel (2004), Kreike et al. (2004), James et al. (2006) and Orchard (2007). A few maintain the above two taxa as distinct species (Colocasia esculenta and Colocasia antiquorum) rather than varieties of Colocasia esculenta (e.g. Onyilagha et al. 1987).

In addition to the above two taxa, others are sometimes recognised, including the following:

Colocasia esculenta var. aquatilis Hassk.

Synonyms: Colocasia esculenta ‘Aquatilis’; Colocasia antiquorum var. aquatilis (Hassk.) Hassk. ex Engl.

This name is applied to wild types of Colocasia esculenta that are found in South West and South East Asia, China, the Ryukyu Islands, Australia and some oceanic islands (and as introduced in USA – see NRCS (2009)). The variety is characterised by having small, poorly developed, acrid, often inedible corms, long lateral stolons, and an absence of daughter corms. It is mainly used for pig food (Yoshino 2002). Exceptionally, the stolons are pickled as a delicacy in Yunnan (Xu et al. 2001).

Works accepting this taxon include Bailey and Bailey (1976), NRCS (2009), Xu et al. (2001), and Orchard (2007).


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Colocasia esculenta var. nymphaeifolia (Vent.) A.F. Hill

Synonyms: Caladium nymphaeifolium Vent.; Arum nymphaeifolium (Vent.) Bull; Colocasia nymphaeifolia (Vent.) Kunth (sometimes incorrectly spelled nymphiifolia).

This variety is found in Japan, under the cultivar name Hasubaimo, and has been introduced to the USA (NRCS 2009). It is characterised by an absence of bending between petiole and leaf blade.

Works accepting this taxon include Hirai et al. (1989) and NRCS (2009).

Colocasia esculenta var. euchlora (K.Koch & Linden) A.F.Hill

Synonyms: Colocasia esculenta ‘Euchlora’; Colocasia euchlora K.Koch & Linden; Colocasia antiquorum var. euchlora (K.Koch & Linden) Engl.

This variety is characterised by deep green leaves with purple margins and petioles, but is now usually only recognised as distinct in gardening books.

In some recent taxonomic works, including Floras and handbooks, there is a tendency to ignore formal varieties, and treat taro as a unitary species with the name Colocasia esculenta (e.g. Smith 1979; Hay 1990; Nasir 1978, Thompson 2000, and Hay 1996). This position was supported by Vinning (2003), quoting the results of the TANSAO Project. The recognition of varieties is, however, supported by others, including Orchard (2007) and others cited above.

For the purposes of this report the following taxa are recognised: Colocasia esculenta (L.) Schott var. esculenta, Colocasia esculenta var. antiquorum (Schott) Hubbard & Rehd. and Colocasia esculenta var. aquatilis Hassk.

Agronomic classifications Of agronomic papers that distinguish different types of taro, almost all use the distinction of dasheen (large corm) and eddoe (small corm) types, rather than the botanical varieties. Most do not define these types, but the consensus seems to be as follows:

Dasheen type (large corm taro) (Figure D.1) Dasheen is the main type grown in Africa, the West Indies, southern Asia and Oceania (Purseglove 1972). The corm is large and cylindrical, up to 30 cm in length and 15 cm in diameter, lacking hairs, with few cormels, and only very rarely, stolons. Sprouting arises from the petiole base, and if this is excised, the remaining corm will usually not sprout, i.e. the corm has a terminal meristem. The central corm is harvested as the main crop, the lateral cormels being discarded or used as planting stock. A portion of the spadix bearing male flower protrudes above the neck of the spathe, and has a very short sterile appendage free of the spathe.


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Figure D.1: A typical dasheen type large corm taro

Eddoe type (small corm taro) (Figure D.2) The eddoe type is the favoured taro in northern Asia, including Japan and China. It is also grown in the West Indies and, to a limited extent, in southern USA (Purseglove 1972). The central corm is small, globoid, and surrounded by cormels (stem tubers) and daughter corms. It has long shaggy hairs in the upper part. If the apex of the corm is removed, the remaining

APEX

BASE

Petiole base and leaf stems

1 cm

Wound where lateral cormel was removed

Fine roots

Remnant scar from the base of the cormel originally used as planting material

Emerging lateral bud


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corm will still sprout readily from lateral buds, i.e. the corm has copious lateral meristems. The lateral cormels and corms constitute the main crop as well as the new planting stock. The central corm is generally considered inedible. The sterile appendage of the spadix is long, three times the length of that in the dasheen type, and is retained within the inrolled tip of the spathe.

Figure D.2: A typical eddoe type small corm taro

Although Figures D.1 and D.2 depict typical large and small taro corms, it should be noted that due to the large number of cultivars recorded, commercially cultivated corms are likely to vary in size and shape, in addition to colour, flavour and texture.

Classification of cultivars Cutting across the botanical and agronomic classifications is a broad classification of many locally recognised cultivars. Some local guides to these cultivars have been produced, as for example, those for 50 cultivars in peninsular Malaya (Ghani 1984), those of Japan (Hirai et al. 1989; Matsuda 2002), Japan and Taiwan (Tanimoto 1990), those of East and South East Asia and Oceania (Yoshino 2002; Lebot et al. 2004), and those of Hawaii (Whitney et al. 1939; James et al. 2006). Cho et al. (2007) discussed the approximately 200 cultivars that may once have existed in Hawaii, compared with only about 75 surviving in official living collections there today.


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These informal classifications, at least the most recent ones, tend not to recognise the traditional division between var. esculenta and var. antiquorum, but instead name informal groups of morphologically and/or genetically similar cultivars. Thus, Ghani (1984) recognised 50 cultivars identified by local names, in four groups and several subgroups in peninsular Malaya. Hirai et al. (1989) recognised 80 cultivars from Japan, divided into nine major groups. Xu et al. (2001) studied 42 samples (with local names) representing 20 cultivars in five major morphotypes in China. Rodríguez Manzano et al. (2001) grouped 42 Cuban clones into six informal groups and several subgroups. Matsuda (2002) recognised 80 cultivars in eleven main cultivar groups in Japan. Lebot et al. (2004) worked on 2298 accessions representing, inter alia, at least 378 cultivars from Vanuatu, 54 from Indonesia, 15 from Malaysia, 19 from the Philippines, 35 from Thailand, and 29 from Vietnam.

Maemouri (2003) reported on a collection of 824 taro accessions representing 594 landraces from just four out of nine provinces of the Solomon Islands. She noted that there was a constant turnover of cultivars in the Solomon Islands, with new forms being continually selected and trialled. In Hawaii, MacCaughey and Emerson (1913, 1914) suggested that there might once have been 150–175 distinct named cultivars of taro in the islands, of which many are now lost. Whitney et al. (1939) recognised 84 distinct types of taro in Hawaii, of which 69 were derived from local plants. James et al. (2006) provided a key to 97 cultivars of taro in the Hawaiian Islands. Of these Hawaiian cultivars, 95 were assigned to var. esculenta, one (Tsuronoko (Araimo)) to var. antiquorum, and one (Zuiki) to Colocasia gigantea.

A number of Colocasia esculenta cultivars are grown as ornamental horticultural subjects under the common name Elephant Ears. There are many of these, but some of the better known ones (Christman 2006) are: • Colocasia esculenta ‘Black Magic’ – dark purple leaves • Colocasia esculenta ‘Jet Black Gold’ – dark purple leaves • Colocasia esculenta ‘Jet Black Wonder’ – dark purple leaves with light coloured veins • Colocasia esculenta ‘Portadora’ – a vigorous form with ruffled leaves • Colocasia esculenta ‘Hilo’ – a dwarf form with variegated leaves • Colocasia esculenta ‘Fontanesia’ (syn. Colocasia esculenta var. fontanesii (Schott ex

Engl.) A.F.Hill) – with violet stems and leaves with wine red veins, margins and petioles • Colocasia esculenta ‘Illustris’ (syn. Colocasia esculenta var. illustris (Bull) A.F.Hill) –

purple markings between the leaf veins

The main taro cultivars Wherever taro is grown there are a multitude of locally recognised cultivars, distinguished by the colour of the tuber flesh (white, pink or red), the colour of the leaf lamina and veins (shades of green, with or without a purple spot on the upper surface above the insertion of the petiole), the colour of the petiole (various shades of green, pinkish purple, almost black, or streaked), and by taste (acridity) of the tubers and leaves. There are many hundreds of cultivars, or perhaps even 15 000 (Ivancic and Lebot 2000), and their nomenclature is complex and inconsistent, with the same or very similar cultivars being grown under different names in different countries. For example, Purseglove (1972) suggested that ‘Common Eddoe’ of the West Indies was the same as ‘Trinidad’ in the USA.

Some of the cultivars grown commercially in the Pacific are: • Akado – Hawaii (Valenzuela and Sato 2004)


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• Dirratengadik – Palau (Brooks 2000) • Lehua Maoli (Maui Lehua) (for poi) – Hawaii (Trujillo et al. 2002; Hamasaki et al. 2000;

Valenzuela and Sato 2004) • Manu’a – American Samoa (Navarro et al. 1986) • Meltalt – Palau (Brooks 2000) • Miyako – Hawaii (Valenzuela and Sato 2004) • Ngeruuch – Palau (Trujillo et al. 2002) • Palau – Samoa (Aregheore and Perera 2003) • Pa'lehua, Pa'akala, and Pauakea – Hawaii (Trujillo et al. 2002) • Pink Samoan – Fiji (Daniells et al. 2004) • Pwetepwet – Samoa (Aregheore and Perera 2003) • Rota (Antiguo) – Northern Marianas (Brooks 2000) • Samoa and Samoa hybrid – Samoa (Jackson et al. 2001) • Taro Niue (Tau(s)ala ni Samoa) – Fiji (Daniells et al. 2004); Hawaii (Valenzuela and Sato

2004); American Samoa (Navarro et al. 1986); Samoa (Jackson et al. 2001) • Toakulu – Samoa (Jackson et al. 2001) • Tsurunoko – Hawaii (Valenzuela and Sato 2004)

In addition there are innumerable locally grown cultivars (see for example Lebot et al. 2004; Cho et al. 2007).

The ‘piko’ group of taro in Hawaii are unusual in that they have hastate leaves (lamina attached by their margin to the petiole) rather than peltate leaves (petiole joins the lamina near the middle) (Onwueme 1999). In Hawaii, 27 main groups of taro cultivars were recognised in 1880. By 1935 only eight main groups were recognised, and many cultivars within each group had been lost (Cho et al. 2007).

In Japan the numerous minor cultivars have been divided into nine main groups on morphological and storage protein characters by Hirai et al. (1989): Eguimo, Dodare, Ishikawa-wase, Tonoimo, Akame, Migashiki, Binroshin, Yatsugashira and Takenokoimo. These cultivar groups included both dasheen and eddoe types. Matsuda (2002) recognised eleven cultivar groups for Japan, based on restriction fragment length polymorphism (RFLP) in rDNA. Most of these corresponded with those of Hirai et al. (1989), but some were different.

In China Xu et al. (2001) grouped 20 traditional cultivars from Yunnan according to ethnobotanical, agro-morphological and genetic characteristics into six major morphotypes: • Inflorescence morphotype (sometimes referred to as Colocasia tonoimo and grown for its

edible inflorescence) – Kaihuayu or kaihua-yutou (Yoshino 2002) • Single-corm morphotype (more or less equivalent to dasheen type) – Daziyu,

Huanggengyu, Lugengdayutou, Shuiyu, Pobule, Byongmanizong • Multicormel morphotype (equivalent, in part, to eddoe type) – Bulena, Bulece, Bulene,

Byongmasongho, Byongmane, Byongmazabyong, Byongmaayo, Bigeana, Bikuobine, Achichibiu, Byongmaayopiu, Qingu, Zhongyu

• Multicorm morphotype (equivalent, in part, to eddoe type) – Gouzhuayu, Mianhuayu, Mibiu

• Petiole morphotype (grown for its edible petioles, corms are of poor quality) – Caiyu


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• Stolon morphotype (more or less equivalent to Colocasia esculenta var. aquatilis) – Wangenyu, Yingjiangyeyu

Taro cultivars grown in Australia

Most taro produced in Australia is broadly categorised as Taro Pacific, the dasheen type, which is also imported from Fiji and Tonga (Vinning 2003). Within this category, the most common cultivars are: • Bun-long or Pan Long Wu, a soft cooking type believed to originate in China (Bown

2000) with white flesh and purple flecks, favoured particularly by the Asian community (Chay-Prove and Goebel 2004; Daniells et al. 2004; Horsburgh and Noller 2005)

• Taro Niue or Tausala ni Samoa, a pink taro sourced from Samoa, favoured particularly by Pacific Islanders (Chay-Prove and Goebel 2004; Daniells et al. 2004)

• Samoan Pink, a white fleshed variety with pink flecks and firm texture from Samoa , favoured particularly by Pacific Islanders (Chay-Prove and Goebel 2004; Daniells et al. 2004)

• Taro Vietnam, a small dasheen type (clear skinned, no hairs) grown mainly as a backyard crop in Queensland and sometimes marketed through Vietnamese grocery shops (Vinning 2003).

Also, various Papua New Guinean dasheen cultivars are grown and eaten locally by Torres Strait Islanders (Chay-Prove and Goebel 2004)

Since about 1998 there has been increasing interest in cultivation of Taro Supreme, the eddoe type of taro, tentatively identified with the Japanese cultivar Ishikawa wase (Vinning 2003). The local cultivar of this form is mainly that known as NORADA 1 (Midmore et al. 2006). Taro Supreme is cultivated particularly in the Northern Rivers district of New South Wales, with smaller plantations in northern Queensland and south-west of Darwin (Vinning 2003; Hicks and Nguyen 2004). Trials are also being undertaken in Western Australia. Processed Taro Supreme is imported into Australia from China as frozen, peeled or brined products, either alone or as mixed vegetables (Vinning 2003).

Taro weed potential Taro propagation, both in cultivation and in the wild, is predominantly by vegetative means (Purseglove 1972; Onwueme 1999). Flowering and seeding in cultivars is rare, with the notable exception of one cultivar (known as Colocasia esculenta ‘Inflorescence morphotype’, Kaihuayu, kaihua-yutou or Colocasia tonoimo) in Yunnan, China, which is grown predominantly for its edible inflorescences (Xu et al. 2001; Yoshino 2002). However, Kreike et al. (2004) noted that flowering and seeding was common in wild type Colocasia esculenta in Indonesia and Papua New Guinea.

The lateral corms of the dasheen type of taro can be removed as propagating material, and in the wild they may give rise to their own crop of daughter corms. A number of wild-type dasheen taro can also form long stolons and propagate and spread from these (Ivancic and Lebot 1999). One selection in Yunnan is cultivated for these stolons (Colocasia esculenta ‘Stolon morphotype’, Wangenyu, Yingjiangyeyu) (Xu et al. 2001).

The eddoe type of taro has a smaller central corm and produces many more (up to 200) daughter corms laterally. These daughter corms are all capable of growing if detached, and


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each will potentially produce a large number of daughter corms of their own in the next season.

In Australia Colocasia esculenta is considered to be native in the Northern Territory, but naturalised in Western Australia, Queensland, New South Wales, and on Christmas Island, Norfolk Island and Lord Howe Island (CHAH 2009). Colocasia esculenta was included in a list of the 200 most invasive plants in South East Queensland by Batianoff and Butler (2002). Hicks and Nguyen (2004) cautioned about disposal of waste corms of the eddoe (var. antiquorum) type, noting that they have the potential to become an invasive weed species. Groves et al. (2005) listed Colocasia esculenta as one of the ten most invasive plants still being sold by nurseries in Queensland, and a problem in some localities in Queensland. Although first recorded as naturalised in Queensland in 1994, it is now known to be spread along many rivers and creeks, with the potential to become a major weed along Queensland’s coasts and in northern NSW.

Colocasia esculenta is listed as invasive in Florida, USA (Florida Exotic Pest Plant Council 2009; Miller et al. 2009; Florida Department of Environmental Protection 2006). Three varieties of this plant are recorded for Florida: Colocasia esculenta var. esculenta, Colocasia esculenta var. antiquorum and Colocasia esculenta var. aquatilis. Thompson (2000) and Christman (2006) indicate most weedy taro plants in the USA are of the stoloniferous form (Colocasia esculenta var. aquatilis). These plants form dense stands along streams, rivers, marshy lakeshores, canals and ditches, and clumps can break loose, forming floating islands that block navigational access and increase flooding potential in canals (Florida Department of Environmental Protection 2006). Colocasia esculenta is listed as potentially noxious in Oklahoma (Oklahoma Department of Wildlife Conservation 2009), and South Carolina (Miller et al. 2009).

Review of import conditions for fresh taro corms References

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Glossary


Additional declaration A statement that is required by an importing country to be entered on a phytosanitary certificate and which provides specific additional information on a consignment in relation to regulated pests (FAO 2010).

Appropriate level of protection (ALOP)

The level of protection deemed appropriate by the Member establishing a sanitary or phytosanitary measure to protect human, animal or plant life or health within its territory (WTO 1995).

Area An officially defined country, part of a country or all or parts of several countries (FAO 2010).

Area of low pest prevalence An area, whether all of a country, part of a country, or all parts of several countries, as identified by the competent authorities, in which a specific pest occurs at low levels and which is subject to effective surveillance, control or eradication measures (FAO 2010).

Biosecurity Australia The unit, within the Biosecurity Services Group, responsible for recommendations for the development of Australia’s biosecurity policy.

Biosecurity Services Group The group responsible for the delivery of biosecurity policy and quarantine services within the Department of Agriculture, Fisheries and Forestry.

Certificate An official document which attests to the phytosanitary status of any consignment affected by phytosanitary regulations (FAO 2010).

Consignment A quantity of plants, plant products and/or other articles being moved from one country to another and covered, when required, by a single phytosanitary certificate (a consignment may be composed of one or more commodities or lots) (FAO 2010).

Control (of a pest) Suppression, containment or eradication of a pest population (FAO 2010).

Dasheen Agronomic name for the large corm variety of taro, Colocasia esculenta var. esculenta.

Eddoe Agronomic name for the small corm variety of taro, Colocasia esculenta var. antiquorum.

Endangered area An area where ecological factors favour the establishment of a pest whose presence in the area will result in economically important loss (FAO 2010).

Entry (of a pest) Movement of a pest into an area where it is not yet present, or present but not widely distributed and being officially controlled (FAO 2010).

Establishment Perpetuation, for the foreseeable future, of a pest within an area after entry (FAO 2010).

Fresh Living; not dried, deep-frozen or otherwise conserved (FAO 2010).

Fruits and vegetables A commodity class for fresh parts of plants intended for consumption or processing and not for planting (FAO 2010).

Host range Species capable, under natural conditions, of sustaining a specific pest or other organism (FAO 2010).

Import Permit Official document authorising importation of a commodity in accordance with specified phytosanitary import requirements (FAO 2010).

Import Risk Analysis An administrative process through which quarantine policy is developed or reviewed, incorporating risk assessment, risk management and risk communication.

Infestation (of a commodity) Official document authorising importation of a commodity in accordance with specified phytosanitary import requirements (FAO 2010).

Inspection Official visual examination of plants, plant products or other regulated articles to determine if pests are present and/or to determine compliance with phytosanitary regulations (FAO 2010).


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Intended use Declared purpose for which plants, plant products, or other regulated articles are imported, produced, or used (FAO 2010).

Interception (of a pest) The detection of a pest during inspection or testing of an imported consignment (FAO 2010).

International Standard for Phytosanitary Measures (ISPM)

An international standard adopted by the Conference of the Food and Agriculture Organization, the Interim Commission on phytosanitary measures or the Commission on phytosanitary measures, established under the IPCC (FAO 2010).

Introduction The entry of a pest resulting in its establishment (FAO 2010).

Lot A number of units of a single commodity, identifiable by its homogeneity of composition, origin etc., forming part of a consignment (FAO 2010).

National Plant Protection Organization (NPPO)

Official service established by a government to discharge the functions specified by the IPPC (FAO 2010).

Official control The active enforcement of mandatory phytosanitary regulations and the application of mandatory phytosanitary procedures with the objective of eradication or containment of quarantine pests or for the management of regulated non-quarantine pests (FAO 2010).

Pathway Any means that allows the entry or spread of a pest (FAO 2010).

Pest Any species, strain or biotype of plant, animal, or pathogenic agent injurious to plants or plant products (FAO 2010).

Pest categorisation The process for determining whether a pest has, or does not have, the characteristics of a quarantine pest or those of a regulated non-quarantine pest (FAO 2010).

Pest Free Area (PFA) An area in which a specific pest does not occur as demonstrated by scientific evidence and in which, where appropriate, this condition is being officially maintained (FAO 2010).

Pest free place of production

Place of production in which a specific pest does not occur as demonstrated by scientific evidence and in which, where appropriate, this condition is being officially maintained for a defined period (FAO 2010).

Pest free production site A defined portion of a place of production in which a specific pest does not occur as demonstrated by scientific evidence and in which, where appropriate, this conditions is being officially maintained for a defined period and that is managed as a separate unit in the same way as a pest free place of production (FAO 2010).

Pest Risk Analysis (PRA) The process of evaluating biological or other scientific and economic evidence to determine whether an organism is a pest, whether it should be regulated, and the strength of any phytosanitary measures to be taken against it (FAO 2010).

Pest risk assessment (for quarantine pests)

Evaluation of the probability of the introduction and spread of a pest and of the associated potential economic consequences (FAO 2010).

Pest risk management (for quarantine pests)

Evaluation and selection of options to reduce the risk of introduction and spread of a pest (FAO 2010).

pH The measure of the acidity or alkalinity of a solution.

Phellogen Plant meristem (growth layer) responsible for secondary growth of a corky protective layer.

Phytosanitary Certificate Certificate patterned after the model certificates of the IPPC (FAO 2010).

Phytosanitary measure Any legislation, regulation or official procedure having the purpose to prevent the introduction and/or spread of quarantine pests, or to limit the economic impact of regulated non-quarantine pests (FAO 2010).

Phytosanitary regulation Official rule to prevent the introduction and/or spread of quarantine pests, or to limit the economic impact of regulated non-quarantine pests, including establishment of procedures for phytosanitary certification (FAO 2010).

Polyphagous Feeding on a relatively large number of hosts from different genera.


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PRA area Area in relation to which a Pest Risk Analysis is conducted (FAO 2010).

Quarantine pest A pest of potential economic importance to the area endangered thereby and not yet present there, or present but not widely distributed and being officially controlled (FAO 2010).

Regulated article Any plant, plant product, storage place, packing, conveyance, container, soil and any other organism, object or material capable of harbouring or spreading pests, deemed to require phytosanitary measures, particularly where international transportation is involved (FAO 2010).

Restricted risk Risk estimate with phytosanitary measure(s) applied.

Spread Expansion of the geographical distribution of a pest within an area (FAO 2010).

SPS Agreement WTO Agreement on the Application of Sanitary and Phytosanitary Measures (WTO 1995).

Stakeholders Government agencies, individuals, community or industry groups or organizations, whether in Australia or overseas, including the proponent/applicant for a specific proposal, who have an interest in the policy issues.

Systems approach(es) The integration of different risk management measures, at least two of which act independently, and which cumulatively achieve the appropriate level of protection against regulated pests (FAO 2010).

Unrestricted risk Unrestricted risk estimates apply in the absence of risk mitigation measures.


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References

Abad ZG, Shew HD, Lucas LT (1994) Characterization and pathogenicity of Pythium species isolated from turfgrass with symptoms of root and crown rot in North Carolina. Phytopathology 84: 913–921.

Abdelzaher HMA, Elnaghy MA (1998) Identification of Pythium carolinianum causing ‘root rot’ of cotton in Egypt and its possible biological control by Pseudomonas fluorescens. Mycopathologia 142: 143–151.

Adams E (2006a) Protecting taro from a menacing beetle. Highlights, SPC Land Resources Division. http://wwwx.spc.int/lrd/Highlights_Archive/highlights_tarobeetle.htm (accessed January 2011).

Adams E (2006b) Finding a control for taro beetle. Land Resources News 2: 2, 11.

AICN (2011) Australian insect common names database. http://www.ento.csiro.au/aicn/index.htm (accessed January 2011).

Ali SS, Geraert E (1975) Helicotylenchus species from Cameroon. Mededlingen van de Faculteit Landbouwwetenschappen Rijksuniversiteit Gent 40: 517–520.

Allow JM, Katcho ZA (1967) Nematode infestation of sugarcane in Iraq. Plant Disease Reporter 51: 809.

APPD (2009) Australian plant pest database. Plant Health Australia. http://www.planthealthaustralia.com.au (accessed November 2009).

AQIS (1999) Draft import risk analysis and proposed phytosanitary requirements for the importation of bulk maize (Zea mays L.) from the United States of America. Australian Quarantine and Inspection Service, Canberra, Australia.

AQIS (2011) AQIS Import conditions database. Department of Agriculture, Fisheries and Forestry, Canberra. http://www.aqis.gov.au/icon/ (accessed January 2011).

Aregheore EM, Perera D (2003) Dry matter, nutrient composition and palatability/acridity of eight exotic cultivars of coco-yams-taro (Colocasia esculenta) in Samoa. Plant Foods for Human Nutrition 58: 1–8.

Awuah RT (1995) Leafspot of taro (Colocasia esculenta (L.) Schott) in Ghana and suppression of symptom development with Thiophanate methyl. African Crop Science Journal 3: 519–523.

Badra T, Caveness FE (1985) Effects of combinations of host genetic variability, nematicides, rainfall and species interactions on nematode community associated with lima beans. Indian Journal of Nematology 14: 77–83.

Bailey LH, Bailey EZ (1976) Hortus third. A concise dictionary of plants cultivated in the United States and Canada. Macmillan, New York, USA.

Baker AD (1959) Some records of plant parasitic nematodes encountered in Canada in 1958. Canadian Insect Pest Review 37: 120–122.

Batianoff GN, Butler DW (2002) Assessment of invasive naturalized plants in south-east Queensland. Plant Protection Quarterly 17: 27–34.


190

Beardsley JW Jr, Gonzalez RH (1975) The biology and ecology of armored scales. Annual Review of Entomology 20: 47–73.

Ben-Dov Y (1994) A systematic catalogue of the mealybugs of the world (Insecta: Homoptera: Coccoidea: Pseudococcidae and Putoideae) with data on geographical distribution, host plants, biology and economic importance. Intercept Ltd, Andover, UK.

Ben-Dov Y, Miller DR, Gibson GAP (2011) ScaleNet. http://www.sel.barc.usda.gov/scalenet/scalenet.htm (accessed May 2011).

Bernhardt EA, Duniway JM (1984) Root and stem rot of parrotfeather (Myriophyllum brasiliense) caused by Pythium carolinianum. Plant Disease 68: 999–1003.

Berniac M (1974) Une maladie bactérienne de Xanthosoma sagittifolium (L.) Schott. Annales de Phytopathologie 6: 197–202.

Berthier Y, Verdier V, Guesdon JL, Chevrier D, Denis JB, Decoux G, Lemattre M (1993) Characterization of Xanthomonas campestris pathovars by rRNA gene restriction patterns. Applied and Environmental Microbiology 59: 851–859.

Blackman RL, Eastop VF (1984) Aphids on the world’s crops: an identification guide. John Wiley & Sons, Chichester, UK.

Bonnardeaux Y, Brundrett M, Batty A, Dixon K, Koch J, Sivasithamparam K (2007) Diversity of mycorrhizal fungi of terrestrial orchids: compatibility webs, brief encounters, lasting relationships and alien invasions. Mycological Research 111: 51–61.

Booth C, Holliday P (1973) Sphaerostilbe repens. Commonwealth Mycological Institute descriptions of pathogenic fungi and bacteria No. 391 (Set 40). CAB International, Wallingford, UK.

Bos L (1999) Plant viruses, unique and intriguing pathogens – a textbook of plant virology. Backhuys Publishers, Leiden, The Netherlands.

Bown D (2000) Aroids: plants of the Arum family. Timber Press, Portland, Oregon, USA.

Brayford D (1987) CMI descriptions of pathogenic fungi and bacteria. No. 926. Cylindrocarpon lichenicola. Mycopathologia 100: 125–126.

Bridge J, Mortimer JJ, Jackson GVH (1983) Hirschmanniella miticausa n. sp. (Nematoda: Pratylenchidae) and its pathogenicity on taro (Colocasia esculenta). Revue de Nématolgie 6: 285–290.

Bridge J, Page SLJ (1984) Plant nematodes of Papua New Guinea: Their importance as crop pests. Report of a plant nematode survey in Papua New Guinea 18 Oct–20 Dec. 1982. CAB Commonwealth Institute of Parasitology, St Albans, UK.

Bridge J, Coyne D, Kwoseh CK (2005) Nematode parasites of tropical root and tuber crops. In Plant parasitic nematodes in subtropical and tropical agriculture 2nd Edition (eds Luc M, Sikora R, Bridge J) pp. 221–258. CAB International, Wallingford, UK.

Bridge J (1988) Plant-parasitic nematode problems in the Pacific islands. Journal of Nematology 20: 173–183.

Brooks FT (1945) Notes on the pathogenicity of Myrothecium roridum Tode ex Fr.. Transactions of the British Mycological Society 27: 155–157.


191

Brooks JG (1965) New records of Coleoptera in Australia. Journal of the Australian Entomological Society 4: 85.

Brooks F (2006) List of plant diseases in American Samoa 2006. Technical Report No. 44. The American Samoa Community College Land Grant Program. Pago Pago, American Samoa.

Brooks F (2000) Cultivar resistance to taro blight disease in American Samoa. Technical Report No. 34, The American Samoa Community College Land Grant Program. College of Tropical Agriculture & Human Resources, University of Hawaii, Manoa, USA.

Brooks FE (2005) Taro leaf blight. The Plant Health Instructor. American Phytopathological Society. http://www.apsnet.org/edcenter/intropp/lessons/fungi/Oomycetes/Pages/TaroLeafBlight.aspx (accessed January 2011).

Browning M, Dawson C, Alm SR, Gorres JH, Amador JA (2004) Differential effects of butyric acid on nematodes from four trophic groups. Applied Soil Ecology 27: 47–54.

Brunt AA, Crabtree K, Dallwitz MJ, Gibbs AJ, Watson L, Zurcher EJ (eds) (1996) Plant viruses online: descriptions and lists from the VIDE database. http://pvo.bio-mirror.cn/refs.htm (accessed January 2011).

CABI (2011) Crop protection compendium. CAB International, Wallingford, UK. http://www.cabi.org/cpc/ (accessed May 2011).

Caetano AC, Boiça Jr. AL (2000) Development of Leptoglossus gonagra Fabr. (Heteroptera: Coreidae) in passionfruit species. Anais da Sociedade Entomológica do Brasil 29: 353–359.

Capelari M, Antonin V, Asai T, Costa H, Ventura JA (2010) A new pathogenic species of Marasmiellus from Brazil. Cryptogamie, Mycologie 31: 137–142.

Carmichael A, Harding R, Jackson G, Kumar S, Lal SN, Masamdu R, Wright J, Clarke AR (2008) TaroPest: an illustrated guide to pests and diseases of taro in the South Pacific. ACIAR Monograph No. 132. http://www.aciar.gov.au/publication/MN132 (accessed January 2011).

Carver M, Gross GF, Woodward TE (1991) Hemiptera. In Insects of Australia (ed Naumann ID) pp. 429–509. Melbourne University Press, Carlton, Australia.

Cassis G, Gross G (1995) Hemiptera: Heteroptera. Australian faunal directory. Australian Biological Resources Study, Canberra. http://www.environment.gov.au/biodiversity/abrs/online-resources/fauna/afd/index.html (accessed January 2011).

Cassis G, Gross G (2002) Hemiptera: Pentatomomorpha. Australian faunal directory. Australian Biological Resources Study, Canberra. http://www.environment.gov.au/biodiversity/abrs/online-resources/fauna/afd/index.html (accessed January 2011).

Cassis G, Houston WWK, Weir TA, Moore BP (1992) Coleoptera: Scaraboidea. In Zoological catalogue of Australia vol. 9 (Ed. Houston WWK) pp. 1–544. Australian Government Publishing Service, Canberra, Australia.

CHAH (2009) Australian Plant Census, a database of plant names for Australia. Council of Heads of Australasian Herbaria. http://www.anbg.gov.au/chah/apc/ (accessed January 2011).

Chase AR, Stall RE, Hodge NC, Jones JB (1992) Characterization of Xanthomonas campestris strains from aroids using physiological, pathological, and fatty acid analyses. Phytopathology 82: 754–759.


192

Chay-Prove P, Goebel R (2004) Taro: the plant. Department of Primary Industries, Queensland.

Cho JJ, Yamakawa RM, Hollyer J (2007) Hawaiian Kalo, Past and Future. Sustainable Agriculture 1: 1–8. Cooperative Extension Service, College of Tropical Agriculture and Human Resources, Manoa, USA.

Choleva BM, Katalan-Gateva S, Tsenkova MK (1980) The nematodes of family Criconematidae Taylor, 1936 (Nematoda Rudolphi, 1808) and family Longidoridae Thorne, 1935, on Rosa damascena Mill. in Bulgaria. Acta Zoologica Bulgarica 14: 64–69.

Choleva B, Peneva V, Brown DJF (1991) Longidorus latocephalus Lamberti, Choleva & Agnostinelli, 1983, a junior synonym of L. pisi Edward, Misra & Singh, 1964 (Nematoda: Dorylaimida). Revue Nématology 14: 505–509.

Christman S (2006) Colocasia esculenta. Floridata website. http://floridata.com/ref/C/colo_esc.cfm (accessed January 2011).

CMI (1968) Sphaerostilbe repens Berk. & Br. Commonwealth Mycological Institute distribution maps of plant diseases. Map No. 288, Edition 2. Agricultural Bureaux, Slough, UK.

Coates DJ, Yen DE, Gaffey PM (1988) Chromosome variation in taro, Colocasia esculenta: implications for origin in the Pacific. Cytologia 53: 551–560.

Common IFB (1990) Moths of Australia. Melbourne University Press, Carlton, Australia.

Constantinescu O (1991) An annotated list of Peronospora names. Thunbergia 15: 1–110.

Cook SCA (1978) Taro Diseases. In Pest control in tropical root crops (eds Anonymous) pp. 177–207. PANS Manual No. 4. Centre for Overseas Pest Research, London, UK.

Cook RP, Dubé AJ (1989) Host-pathogen index of plant diseases in South Australia. South Australian Department of Agriculture.

Copland MJW; Ibrahim AG (1985) Biology of glasshouse scale insects and their parasitoids. In: Biological pest control. The glasshouse experience (Ed. Hussey NW, Scopes NEA) pp. 87–90. Blandford Press, Poole, UK.

Cother EJ, Gilbert RL (1992) Distribution of Pythium arrhenomanes in rice-growing soils of southern New South Wales. Australasian Plant Pathology 21: 79–82.

Cowie ID, Albrecht DA (eds) (2005) Checklist of NT vascular plant species. Northern Territory Government, Darwin, Australia.

CSIRO (2009) World Thysanoptera. CSIRO Entomology, Canberra, Australia. http://anic.ento.csiro.au/thrips/identifying_thrips/thrips_a-z.html (accessed January 2011).

CTAHR (2002) CTAHR solves the mystery of Taro Pocket Rot! University of Hawaii at Mānoa. http://www.ctahr.hawaii.edu/ctahr2001/CTAHRInAction/Apr_02/TaroPocketRot.asp (accessed January 2011).

Cunnington J (2003) Pathogenic fungi on introduced plants in Victoria. A host list and literature guide for their identification. Victoria Department of Primary Industries, Knoxfield, Australia.

Cybertruffle (2007) Cybernome. The nomenclator for fungi and their associated organisms. http://www.cybertruffle.org.uk/cybernome/eng/index.htm (accessed January 2011).


193

Daniells J, Petinaud P, Salleras P (2004) Taro. In The new crop industries handbook (eds Salvin S, Bourke M, Byrne T) pp. 90–96. RIRDC Publication 04/125. Rural Industries Research and Development Corporation, Canberra, Australia.

Daniells J, Hughes M, Traynor M, Vawdrey L, Astridge D (2009) Taro industry development in Australia: the first steps. RIRDC Publication 09/066. Rural Industries Research and Development Corporation, Canberra, Australia.

Davis RI, McMichael LA, Maireroa N, Wigmore WJ (2005) Surveys for plant diseases caused by viruses and virus-like pathogens in the Cook Islands. SPC Technical Paper No. 222. Secretariat of the Pacific Community, Suva, Fiji.

Davis RI, Tupouniua SK, Amice R, Taufa L, Jones P (2006) Surveys for plant diseases caused by viruses and virus-like pathogens in Tonga and New Caledonia. SPC Technical Paper No. 224. Secretariat of the Pacific Community, Suva, Fiji.

Devasahayam S, Abdulla Koya KM (2005) Insect Pests of Ginger. In Ginger: the genus Zingiber (eds Ravindran PN, Nirmal Babu K) pp. 367–389. CRC Press, Boca Raton, USA.

Devitt LC, Hafner G, Dale JL, Harding RM (2001) Partial characterisation of a new dsRNA virus infecting taro. In Abstracts of the 1st Australian virology group meeting. Australian Society for Microbiology, Parkville, Australia.

Diaz A, Okabe K, Eckenrode CJ, Villani MG, OConnor BM (2000) Biology, ecology, and management of the bulb mites of the genus Rhizoglyphus (Acari: Acaridae). Experimental and Applied Acarology 24: 85–113.

Dingley JM, Fullerton RA, McKenzie EHC (1981) Survey of agricultural pests and diseases. Technical Report Volume 2. Records of fungi, bacteria, algae and angiosperms pathogenic on plants in Cook Islands, Fiji, Kiribati, Niue, Tonga, Tuvalu and Western Samoa. South Pacific Bureau for Economic Co-operation, United Nations Development Programme, Food and Agriculture Organization of the United Nations.

Dong JH, Cheng XF, Yin YY, Fang Q, Ding M, Li TT, Zhang LZ, Su XX, McBeath JH, Zhang ZK (2008) Characterization of tomato zonate spot virus, a new tospovirus in China. Archives of Virology 153: 855–864.

Dowson WJ (1943) On the generic names Pseudomonas, Xanthomonas and Bacterium for certain bacterial plant pathogens. Transactions of the British Mycological Society 27: 3–14.

Dye DW, Bradbury MG, Hayward AC, Lelliot RA, Schroth MN (1980) International standards for naming pathovars of phytopathogenic bacteria and a list of pathovar names and pathotype strains. Review of Plant Pathology 59: 153–168.

Ecoport (2011) Ecoport – the consilience engine. http://ecoport.org/ (accessed January 2011).

El-Tigani, Elamin M, Siddiqi MR (1970) Incidence of plant parasitic nematodes in the northern Fung area, the Sudan. FAO Plant Protection Bulletin 18: 102–106.

Elliott MS, Zettler FW, Brown LG (1997) Dasheen mosaic potyvirus of edible and ornamental aroids. Florida Department of Agriculture and Consumer Services, Plant Pathology Circular No. 384, Florida, USA.


194

EPBC (1999) List of Threatened Flora. Environment Protection and Biodiversity Conservation Act 1999. Australian Government Department of Sustainability, Environment, Water, Population and Communities, Canberra, Australia. http://www.environment.gov.au/epbc/about/lists.html#species (accessed January 2011).

EPPO (2004) Xanthomonas axonopodis pv. dieffenbachiae. Diagnostic protocols for regulated pests. European and Mediterranean Plant Protection Organisation. http://archives.eppo.org/EPPOStandards/PM7_DIAGNOS/pm7-23(1).pdf (accessed January 2011).

EPPO (2011a) Xanthomonas axonopodis pv. dieffenbachiae. Data Sheets on Quarantine Pests. European and Mediterranean Plant Protection Organisation. http://www.eppo.org/QUARANTINE/bacteria/Xanthomonas_dieffenbachiae/XANTDF_ds.pdf (accessed January 2011).

EPPO (2011b) Aphelenchoides besseyi. Data Sheets on Quarantine Pests. European and Mediterranean Plant Protection Organisation. http://www.eppo.org/QUARANTINE/nematodes/Aphelenchoides_besseyi/APLOBE_ds.pdf (accessed January 2011).

EPPO (2011c) EPPO Plant Protection Thesaurus. European and Mediterranean Plant Protection Organisation. http://eppt.eppo.org/# (accessed January 2011).

Erwin DC, Ribeiro OK (1996) Phytophthora diseases worldwide. APS Press, St. Paul, Minneapolis, USA.

Evans AAF (1998) Reproductive Mechanisms. In The physiology and biochemistry of free-living and plant-parasitic nematodes (eds Perry RN, Wright DJ) pp. 133–154. CABI Publishing, Wallingford, UK.

Fakalata O (1981) Weevil pest on kava stems in Vava'u (Tonga). Alafua Agricultural Bulletin 6: 39–39.

Fan Q, Zhang Z (2003) Rhizoglyphus echinopus and Rhizoglyphus robini (Acari: Acaridae) from Australia and New Zealand: identification, host plants and geographical distribution. Systematic & Applied Acarology Special Publications 16: 1-16.

FAO (2001a) International Standards for Phytosanitary Measures – No. 13 Guidelines for the Notification of Non-compliance and Emergency Action. Food and Agriculture Organization of the United Nations, Rome, Italy. https://www.ippc.int/IPP/En/default.jsp (accessed January 2011).

FAO (2001b) International Standards for Phytosanitary Measures – No. 12 Guidelines for Phytosanitary Certificates. Food and Agriculture Organization of the United Nations, Rome, Italy. https://www.ippc.int/IPP/En/default.jsp (accessed January 2011).

FAO (2003) Selected indicators of food and agriculture development in the Asia-Pacific region 1992-2002. Food and Agriculture Organization of the United Nations. RAP Publication 2003/10. ftp://ftp.fao.org/docrep/fao/004/AD452e/ad452e00.pdf (accessed January 2011).

FAO (2004) International Standards for Phytosanitary Measures – No. 11 Pest Risk Analysis for Quarantine Pests Including Analysis of Environmental Risks and Living Modified Organisms. Food and Agriculture Organization of the United Nations, Rome, Italy. https://www.ippc.int/IPP/En/default.jsp (accessed January 2011).


195

FAO (2007) International Standards for Phytosanitary Measures – No. 2 Framework for Pest Risk Analysis. Food and Agriculture Organization of the United Nations, Rome, Italy. https://www.ippc.int/IPP/En/default.jsp (accessed January 2011).

FAO (2011) FAO Economic and Social Department. The Statistics Division. Major Food and Agricultural Commodities and Producers. http://faostat.fao.org/default.aspx (accessed September 2011).

FAO (2010) International Standards for Phytosanitary Measures – No. 5 Glossary of Phytosanitary Terms. https://www.ippc.int/IPP/En/default.jsp (accessed January 2011).

Farr DF, Rossman AY (2011) Fungal databases. Systematic Botany & Mycology Laboratory, ARS, USDA. http://nt.ars-grin.gov/fungaldatabases (accessed January 2011).

Farreyrol K, Pearson MN, Grisoni M, Cohen D, Beck D (2006) Vanilla mosaic virus isolates from French Polynesia and the Cook Islands are Dasheen mosaic virus strains that exclusively infect vanilla. Archives of Virology 151: 905–19.

Fatuesi S, Vargo AM (1995) An initial evaluation of biological and cultural controls of taro pests in American Samoa. Technical Report No. 26. American Samoa Land Grant Program, Pago Pago, American Samoa.

Fauna Europaea (2009) Fauna Europaea. http://www.faunaeur.org/ (accessed January 2011).

Fauquet CM, Mayo MA, Maniloff J, Desselberger U, Ball LA (eds) (2005) Virus taxonomy: classification and nomenclature of viruses: eighth report of the International Committee on the Taxonomy of Viruses. Elsevier Academic Press, London, UK.

Ferris H (1999) Longidorus. Nemaplex – the nematode-plant expert information system. http://plpnemweb.ucdavis.edu/Nemaplex/Taxadata/G068.HTM (accessed January 2011).

Florida Department of Environmental Protection (2006) Weed Alert. Wild Taro (Colocasia esculenta). http://plants.ifas.ufl.edu/education/digital_teacher_notebook_june_2007/part_4/DEP%20Weed%20Alerts/14_DEP%20Wild%20Taro.pdf (accessed January 2011).

Florida Exotic Pest Plant Council (2009) Invasive plant list. http://www.fleppc.org (accessed January 2011).

Follett PA, Alontaga D, Tom R, Weinert ED, Tsuda D, Kinney K (2007) Absence of the quarantine pest Elytroteinus subtruncatus in East Hawaii sweetpotato fields. Proceedings of the Hawaiian Entomological Society 39: 33–38.

Forsberg LI (1985) Foliar diseases of nursery-grown ornamental palms in Queensland. Australasian Plant Pathology 14: 67–71.

French BR (2006) Insect pests of food plants of Papua New Guinea. http://foodplantsinternational.com/resources/3Insects%20on%20food%20plants%20in%20PNG.pdf (accessed January 2011).

Frison EA, Putter CAJ (1993) FAO/IBPGR technical guidelines for the safe movement of coconut germplasm. Food and Agriculture Organization of the United Nations, Rome/International Board for Plant Genetic Resources, Rome.

Frohlich J, Hyde KD, Guest DI (1997) Fungi associated with leaf spots of palms in north Queensland, Australia. Mycological Research 101: 721–732.


196

Galbraith JC (1987) The pathogenicity of an Australian isolate of Acremonium zonatum to water hyacinth, and its relationship with the biological control agent, Neochetina eichhorniae. Australian Journal of Agricultural Research 38: 219–229.

Gerlach WWP (1988) Plant diseases of Western Samoa. Samoan German Crop Protection Project, Apia, Western Samoa.

Ghani FD (1984) Keys to the cultivars of Keladi (Colocasia esculenta Araceae) in Peninsular Malaysia. Gardens Bulletin Singapore 37: 199–208.

Gibbs A, Harrison B (1976) Plant virology - the principles. Edward Arnold, London, UK.

Gibbs AJ, Mackenzie AM, Wei KJ, Gibbs MJ (2008a) The potyviruses of Australia. Archives of Virology 153: 1411–20.

Gibbs AJ, Ohshima K, Phillips MJ, Gibbs MJ (2008b) The prehistory of potyviruses: their initial radiation was during the dawn of agriculture. PLoS ONE 3, e2523. http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=2429970&blobtype=pdf (accessed January 2011).

Glassey K (2006) Hot dip for taro. Biosecurity 70: 16.

Gollifer DE, Jackson GVH, Dabek AJ, Plumb RT (1978) Incidence, and effects on yield, of virus diseases of taro (Colocasia esculenta) in the Solomon Islands. Annals of Applied Biology 88: 131–135.

Gollifer DE, Jackson GVH, Newhook FJ (1980) Survival of inoculum of the leaf blight fungus Phytophthora colocasiae infecting taro, Colocasia esculenta in the Solomon Islands. Annals of Applied Biology 94: 379–390.

Goos RD (1962) The occurrence of Sphaerostilbe repens in Central American soils. American Journal of Botany 49: 19–23.

Greber RS (1987) Dasheen mosaic potyvirus. In Viruses of plants in Australia (eds Büchen-Osmond C, Crabtree K, Gibbs A, McLean G). Australian National University, Canberra, Australia. http://www.ictvdb.rothamsted.ac.uk/Aussi/aussi.htm (accessed January 2011).

Greber RS, Shaw DE (1986) Dasheen mosaic virus in Queensland. Australasian Plant Pathology 15: 29–33.

Green RJ, Skotland CB (1993) Diseases of mint (Mentha piperita L., M. cardiaca Baker, M. spicata L. and M. arvensis L.). APSnet, Common Names of Plant Diseases. http://www.apsnet.org/publications/commonnames/Pages/Mint.aspx (accessed January 2011).

Gross GF (1991) Superfamily Coreoidea. In The insects of Australia. A textbook for students and research workers. Vol. 1, 2nd edn. (Ed. Naumann ID) pp. 503–504. Melbourne University Press, Carlton, Australia.

Groves RH, Boden R, Lonsdale WM (2005) Jumping the garden fence: invasive garden plants in Australia and their environmental and agricultural impacts. WWF-Australia, Sydney and CSIRO, Canberra, Australia. http://www.wwf.org.au/publications/jumping_the_garden_fence/ (accessed January 2011).

Gutierrez J, Schicha E (1983) The spider mite family Tetranychidae (Acari) in New South Wales. International Journal of Acarology 9: 99–116.


197

Halliday B (2000) Arachnida: Acarina. Australian faunal directory. Australian Biological Resources Study, Canberra. http://www.environment.gov.au/biodiversity/abrs/online-resources/fauna/afd/index.html (accessed January 2011).

Hamasaki R, Sato HD, Arakaki A, Shimabuku R, Fukuda S, Sato D, Yoshino R, Kanehiro N (2000) Leaf blight tolerant taro varieties: promoting grower adoption and food processor acceptance. Project 16-914 final report. http://www.extento.hawaii.edu/IPM/taro/tarofinal.htm (accessed January 2011).

Hammes C, Chant H, Mu L (1989) Manuel de Défense des Cultures en Polynésie Française. Institut Français de Recherche Scientifique pour le Dévelppement en Coopération. Service de L'économie Rurale de Polynésie Français. Entomologie Agricole. Notes et documents No 3. ORSTOM Tahiti, French Polynesia.

Hashemi SR, Kheyri A (2003) Plant parasitic nematodes associated with Juniper forests in Qazvin Province. Iranian Journal of Forest and Range Protection Research 1: 37–57.

Hashim Z (1983) Description of Pratylenchus jordanensis n. sp. (Nematoda: Tylenchida) and notes on other Tylenchida from Jordan. Revue Nématologique 6: 187–192.

Hawaii Department of Agriculture (2009) Plant pest control. Persisting biological control problems. http://hawaii.gov/hdoa/pi/ppc/backup-files/bioprob/ (accessed January 2011).

Hay A (1990) Aroids of Papua New Guinea. Christensen Research Institute, Madang, Papua New Guinea.

Hay A (1996) A new Bornean species of Colocasia Schott (Araceae: Colocasieae), with a synopsis of the genus in Malesia and Australia. Sandakania 7: 31–48.

Hicks D, Nguyen VQ (2004) Japanese taro (Sato-imo). In The new crop industries handbook (eds Salvin S, Bourke M, Byrne T) pp. 66–72. RIRDC Publication 04/125. Rural Industries Research and Development Corporation, Canberra, Australia.

Hirai M, Saito T, Takayanaji K (1989) Classification of Japanese cultivars of taro (Colocasia esculenta (L.) Schott) based on electrophoretic pattern of the tuber proteins and morphological characters. Japanese Journal of Breeding 39: 307–317.

Hooper DJ (1961) A redescription of Longidorus elongatus (de Man, 1876) Thorne & Swanger, 1936, (Nematoda, Dorylaimidae) and descriptions of five new species of Longidorus from Great Britain. Nematologica 6: 237–257.

Horsburgh C, Noller J (2005) Exotic tropical fruits and vegetables. Category marketing opportunities. RIRDC Publication No 05/112. Rural Industries Research and Development Corporation, Canberra, Australia.

Hu JS, Meleisea S, Wang M, Shaarawy MA, Zettler FW (1995) Dasheen mosaic potyvirus in Hawaiian taro. Australasian Plant Pathology 24: 112–117.

Hunter DG, Shafia A (2000) Diseases of crops in the Maldives. Australasian Plant Pathology 29: 184–189.

Hussey RS, Grundler FMW (1998) Nematode parasitism of plants. In The physiology and biochemistry of free-living and plant-parasitic nematodes (eds Perry RN, Wright DJ) pp. 213–243. CABI Publishing, Wallingford, UK.


198

Hyde KD, Alcorn JL (1993) Some disease-associated microorganisms on plants of Cape York Peninsula and Torres Strait Islands. Australasian Plant Pathology 22: 73–83.

Ibrahim IKA, Handoo ZA, El-Sherbiny AA (2000) A survey of phytoparasitic nematodes on cultivated and non-cultivated plants in northwestern Egypt. Supplement to the Journal of Nematology 32: 478–485.

Ishibashi N, Takayama S, Kondo E (2005) Propagation and feeding behaviour of the mycetophagous nematode, Aphelenchus avenae, on four species of soil fungi. Japanese Journal of Nematology 35: 13–19.

Ivancic A, Lebot V (1999) Botany and genetics of New Caledonian wild taro, Colocasia esculenta. Pacific Science 53: 273–285.

Ivancic A, Lebot V (2000) The genetics and breeding of taro. Cirad, Montpellier, France.

Jackson AO, Dietzgen RG, Goodin MM, Brag JN, Deng M (2005) Biology of plant rhabdoviruses. Annual Review of Phytopathology 43: 623–660.

Jackson G, Gollifer D (1975) Storage rots of taro (Colocasia esculenta L. Schott) in the British Solomon Islands. Annals of Applied Biology 80: 217–230.

Jackson GVH (1978) Alomae and bobone diseases of taro. SPC Advisory Leaflet No. 8, South Pacific Commission, Noumea, New Caledonia.

Jackson GVH (1980) Diseases and pests of taro. South Pacific Commission, Noumea, New Caledonia.

Jackson GVH, Gerlach WWP (1985) Pythium rots of taro. South Pacific Commission, Pest Advisory Leaflet No. 20, Noumea, New Caledonia.

Jackson GVH (1999) Taro leaf blight. Plant Protection Service, Secretariat of the Pacific Community, Pest Advisory Leaflet No. 3, Noumea, New Caledonia.

Jackson GVH, Volsoni F, Kumar J, Pearson MN, Morton JR (2001) Comparison of the growth of in vitro produced pathogen-tested Colocasia taro and field-collected planting material. New Zealand Journal of Crop and Horticultural Science 29: 171–176.

James M, Kenton RT, Woods RD (1973) Viruslike particles associated with two diseases of Colocasia esculenta (L.) Schott in the Solomon Islands. Journal of General Virology 21: 145–153.

James S, Van Dyke P, Igeta K, Harbottle A (2006) Hawaiian kalo. An identification guide for taro in the Hawaiian Islands. Bishop Museum, Honolulu. http://hbs.bishopmuseum.org/botany/taro/HawaiianKalo.html (accessed January 2011).

Janes BS (1962) Experiments in the control of Pithomyces chartarum by fungicides. Australian Journal of Experimental Agriculture and Animal Husbandry 2: 141–147.

Jatala P, Bridge J (1990) Nematode parasites of root and tuber crops. In Plant parasitic nematodes in subtropical and tropical agriculture (eds Luc M, Sikora RA, Bridge J) pp. 137–180. CAB International, Wallingford, UK.

Jensen HJ, Horner CE (1957) Peppermint decline caused by Longidorus sylphus can be controlled by soil fumigation. Phytopathology 47: 18.


199

JSCC (2009) Rhizostilbella hibisci. Japan Society for Culture Collections. http://www.nbrc.nite.go.jp/jscc/idb/strains?Snt=0&Sn=Rhizostilbella+hibisci (accessed January 2011).

Jones DR, Shaw DE, Gowanlock DH (1980) Bacilliform virus particles detected in Cyrtosperma sp. imported from Solomon Islands. Australasian Plant Pathology 9: 5–6.

Jones R, Meehan B (1989) Plant foods of the Gidjingali: Ethnographic and archaeological perspectives from northern Australia on tuber and seed exploration. In Foraging and farming: the evolution of plant exploitation (eds Harris DR, Hillman GC) pp. 120–135. Unwin Hyman, London, UK.

Katalan-Gateva S (1980) Plant parasitic nematodes from the families Longidoridae and Hoplolaimidae in the rhizosphere of fruit trees in south-western Bulgaria. Khelmintologiya 10: 29-37.

Katcho ZA, Allow JM (1969) Some new records of plant-parasitic nematodes from Iraq. Bulletin of the Iraq Natural History Museum 4: 15–20.

Kay DE (1973) Root crops. Tropical Products Institute, Foreign & Commonwealth Office, London, UK.

Kazi (1996) Taxonomic studies on the plant parasitic nematodes belonging to the family Hoplolaimidae with special reference to genus Helicotylenchus. Ph.D. thesis, University of Karachi, Pakistan. http://prr.hec.gov.pk/Thesis/846.pdf (accessed November 2009).

Kirby MF, Kirby ME, Siddiqi MR, Loof PAA (1980) Fiji nematode survey report: plant parasitic nematode distributions and host associations. Report No. 68. Ministry of Agriculture and Fisheries, Suva, Fiji.

Kirk PM (1991) Apiospora montagnei. IMI descriptions of fungi and bacteria No. 1052. Set No. 106. CAB International, Wallingford, UK.

Konicek DE (1961) Ecology of Longidorus menthasolanus Konicek and Jensen 1961, a parasite of peppermint in Oregon. Dissertation Abstracts 22: 963.

Konicek DE, Jensen HJ (1961) Longidorus menthasolanus, a new plant parasite from Oregon (Nemata: Dorylaimoidea). Proceedings of the Helminthological Society of Washington 28: 216–218.

Koteja J (1990) Developmental biology and physiology: life history. In Armoured scale insects – their biology, natural enemies and control. World Crop Pests Volume 4A (ed Rosen D) pp. 243–254. Elsevier, Amsterdam, The Netherlands.

Kreike CM, Van Eck HJ, Lebot V (2004) Genetic diversity of taro, Colocasia esculenta (L.) Schott, in Southeast Asia and the Pacific. Theoretical and Applied Genetics 109: 761–768.

Laguna IG, Salazar LG, López JF (1983) Fungal and bacterial diseases of aroids: Xanthosoma spp. and Colocasia esculenta (L.) Schott in Costa Rica. Technical Bulletin No. 10. Tropical Agricultural Training and Research Center (CATIE), Turrialba, Costa Rica.

Lal M, Khan E (1993) On the taxonomic status of species of Helicotylenchus Steiner, 1945. 1. having a digitate type tail terminus from India. Indian Journal of Nematology 23: 110–117.

Lamberti F (1997) Plant nematology in developing countries: Problems and progress. In Plant nematode problems and their control in the Near East region (eds Maqbool MA, Kerry B) FAO Plant Production and Protection Paper - 144. http://www.fao.org/docrep/v9978e/v9978e00.HTM (accessed January 2011).


200

Landcare Research (2009) New Zealand Fungi. http://nzfungi.landcareresearch.co.nz/html/mycology.asp (accessed January 2011).

Lebot V, Aradhya KM (1991) Isozyme variation in taro (Colocasia esculenta (L.) Schott) from Asia and Oceania. Euphytica 56: 55–56.

Lebot V, Prana MS, Kreike N, van Heck H, Pardales J, Okpul T, Gendua T, Thongjiem M, Hue H, Viet N, Yap TC (2004) Characterisation of taro (Colocasia esculenta (L.) Schott) genetic resources in Southeast Asia and Oceania. Genetic Resources & Crop Evolution 51: 381–392.

Lehman PS (2002) Phytoparasitic Nematodes Reported From Florida. Florida Department of Agriculture & Consumer Services. http://www.doacs.state.fl.us/pi/enpp/nema/images/phyotnema.pdf (accessed January 2011).

Lemin CD (2006) Taro production mechanisation and industry development. Rural Industries Research and Development Corporation, Publication No. 06/019, Canberra, Australia.

Leong SL (2005) Black Aspergillus species: implications for ochratoxin A in Australian grapes and wine. Ph.D. thesis. School of Agriculture and Wine. University of Adelaide, Adelaide, Australia.

Letham DB (1995) Host-pathogen index of plant diseases in New South Wales. New South Wales Agriculture, Rydalmere, Australia.

Li CS (1993) Review of the Australian Epilachninae (Coleoptera: Coccinellidae). Journal of the Australian Entomological Society 32: 209–224.

Liloqula R, Saelea J, Levela H (1993) Traditional taro cultivation in the Solomon Islands. In Proceedings of the sustainable taro culture for the Pacific conference, Honolulu, Hawaii, 1992 (Ed. Ferentinos L) pp. 125–131. University of Hawaii, Honolulu, Hawaii.

Lin MJ, Ko WH (2008) Occurrence of isolates of Phytophthora colocasiae in Taiwan with homothallic behaviour and its significance. Mycologia 100: 727–735.

Lipp RL, Alvarez AM, Benedict AA, Berestecky J (1992) Use of monoclonal antibodies and pathogenicity tests to characterize strains of Xanthomonas campestris pv. dieffenbachiae from aroids. Phytopathology 82: 677–682.

Luc M, Sikora RA, Bridge J (1990) Plant parasitic nematodes in subtropical and tropical agriculture. CAB International, Wallingford, UK.

Macanawai AR, Ebenebe AA, Hunter D, Devitt LC, Hafner GJ, Harding RM (2005) Investigations into the seed and mealybug transmission of Taro bacilliform virus. Australasian Plant Pathology 34: 73–76.

MacCaughey V, Emerson JS (1913) The kalo of Hawaii. Hawaiian Forester and Agriculturalist 10: 186–193, 225–231, 280–288, 315–323, 349–358, 371–375.

MacCaughey V, Emerson JS (1914) The kalo of Hawaii. Hawaiian Forester and Agriculturalist 11: 17–23, 44–51, 111–122, 201–216.

Macfarlane R (1987) Papuana beetles. South Pacific Commission, Pest Advisory Leaflet 21, Noumea, New Caledonia.

Macfarlane R (1999) Patchiella reaumuri. Ecoport. http://ecoport.org/ep?Arthropod=19077&entityType=AR****&entityDisplayCategory=full (accessed January 2011).


201

Maddison P A (1993) UNDP/FAO-SPEC Survey of Agricultural Pests and Diseases in the South Pacific, Technical report, Volume 3: Pests and other fauna associated with plants, with botanical accounts of plants. Manaaki Whenua - Landcare Research, Auckland, New Zealand. http://nzac.landcareresearch.co.nz/ (accessed November 2010).

Maddison PA, Crosby TK (2009) Summary of plant-animal associations from ‘Maddison (1993) Pests and other fauna associated with plants, with botanical accounts of plants’. Manaaki Whenua - Landcare Research, Auckland, New Zealand. http://nzac.landcareresearch.co.nz/ (accessed January 2011).

Maemouri RK (2003) Promoting on-farm conservation of taro through diversity fairs in the Solomon Islands. Planting Material Network, Solomon Islands. http://www.terracircle.org.au/pmn/report/diversity_fairs_taro.html (accessed January 2011).

Magee CP, McCleery FC (1937) The occurrence of plant diseases in New South Wales with particular reference to the three-year period ending 30th June, 1936. Scientific Bulletin of the Department of Agriculture, New South Wales 57: 1–42.

Maggiorani A, Bracamonte L, Molmquist O, Cadenas A, Briceno E, Renaud J (2004) The identification of species of the genus Helicotylenchus (Nematoda) in Venezuela. Part 1. Revista Forestal Venezolana 48: 81–86.

Magsig-Castillo J, Morse JG, Walker GP, Bi JL, Rugman-Jones PF, Stouthamer R (2010) Phoretic dispersal of armoured scale crawlers (Hemiptera: Diaspididae). Journal of Economic Entomology 103: 1172–1179.

Manzanilla-López RH, Evans K, Bridge J (2004) Plant diseases caused by nematodes. In Nematology – advances and perspectives, Volume 2 (eds Chen ZX, Chen SY, Dickson DW) pp. 637–716 . Tsinghua University Press, Beijing, China and CABI Publishing, Wallingford, UK.

Marais M, Buckley NH (1992) External morphology of eight South African Helicotylenchus species (Hoplolaimidae: Nemata). Phytophylactica 24: 297–306.

Marais M, van den Berg E, Queneherve P, Tiedt LR (1999) Description of Helicotylenchus kermarreci n. sp., with notes on some Helicotylenchus Steiner, 1945 and a Rotylenchus Filip'ev, 1936 species (Nemata: Hoplolaimidae) from the Guadeloupe Islands, French West Indies. Journal of Nematode Morphology and Systematics 2: 159–172.

Martin JH, Gillespie PS (2009) Aleurodicus destructor Mackie, 1912. Australian faunal directory. Australian Biological Resources Study, Canberra. http://www.environment.gov.au/biodiversity/abrs/online-resources/fauna/afd/index.html (accessed January 2011).

Martin Kessing JL, Mau FL (1992) Lamenia caliginea (Stal). Crop Knowledge Master, Extension Entomology & UH-CTAHR Integrated Pest Management Program. http://www.extento.hawaii.edu/kbase/crop/Type/l_caligi.htm (accessed January 2011).

Martin Kessing JL, Mau FL (1993) Aleurodicus dispersus (Russell). Crop Knowledge Master, Extension Entomology & UH-CTAHR Integrated Pest Management Program. http://www.extento.hawaii.edu/kbase/Crop/Type/a_disper.htm (accessed January 2011).

Martin Kessing JL, Mau FL, Diez JM (2007) Aspidiotus destructor (Signoret). Crop Knowledge Master, Extension Entomology & UH-CTAHR Integrated Pest Management Program. http://www.extento.hawaii.edu/kbase/crop/Type/a_destru.htm (accessed January 2011).


202

Masamdu R, Simbiken N (2000) Effect of taro beetles on taro production in PNG. In Food security for Papua New Guinea. Proceedings of the Papua New Guinea food and nutrition conference, PNG University of Technology, Lae, 26-30 June 2000 (eds Bourke RM, Allen MG, Salisbury JG) ACIAR Proceedings No. 99, pp. 752–757. Australian Centre for International Agricultural Research, Canberra, Australia.

Matsuda M (2002) Taro in Japan, and its dispersal in east and South East Asia. In Vegeculture in eastern Asia and Oceania (eds Yoshida S, Matthews PJ), JCAS Symposium Series 16, pp. 117–134. Japan Centre for Area Studies, Osaka, Japan.

Matthews PJ, Terauchi R (1994) The genetics of agriculture: DNA variation in taro and yam. In Tropical archaeobotany (Ed. Hather J) pp. 251–262. Routledge, London, UK.

Matthews PJ (2003) Taro planthoppers (Tarophagus spp.) in Australia and the origins of taro (Colocasia esculenta) in Oceania. Archaeology in Oceania 38: 192–202.

Mau FL, Martin Kessing JL (1992a) Elytroteinus subtruncatus (Fairmaire). Crop Knowledge Master, Extension Entomology & UH-CTAHR Integrated Pest Management Program. http://www.extento.hawaii.edu/kbase/crop/Type/elytrote.htm (accessed January 2011).

Mau FL. Martin Kessing JL (1992b) Aspidiella hartii (Cockerell). University of Hawaii Crop Knowledge Master. http://www.extento.hawaii.edu/kbase/crop/type/a_hartii.htm (accessed May 2011).

Mau FL, Martin Kessing JL, Tenbrink VL, Hara AH (1994) Pentalonia nigroneruosa (Coquerel). Crop Knowledge Master, Extension Entomology & UH-CTAHR Integrated Pest Management Program. http://www.extento.hawaii.edu/Kbase/crop/Type/pentalon.htm (accessed January 2011).

Mau FL, Martin Kessing JL, Diez JM (2007) Tetranychus cinnabarinus (Boisduval). Crop Knowledge Master, Extension Entomology & UH-CTAHR Integrated Pest Management Program. http://www.extento.hawaii.edu/kbase/crop/Type/t_cinnab.htm (accessed January 2011).

May BM (1993) Larvae of Curculionoidea (Insecta: Coleoptera): a systematic overview. Fauna of New Zealand Number 28. Manaaki Whenua Press, Christchurch, New Zealand.

McCormack G (2007) Cook Islands Biodiversity Database, Version 2007.1. Cook Islands Natural Heritage Trust, Rarotonga. Bishop Museum. http://cookislands.bishopmuseum.org/species.asp?id=14509 (accessed January 2011).

McGlashan H (2006) Battling the beetle. In Partners in research for development. pp. 8–9. Australian Centre for International Agricultural Research, Canberra, Australia.

McKenzie EHC, Jackson GVH (1986) The fungi, bacteria and pathogenic algae of Solomon Islands. Strengthening Plant Protection and Root Crops Development in the South Pacific. FAO. RAS/83/001, Field Document 11. Suva, Fiji.

McKenzie EHC, Jackson GVH (1990) The fungi, bacteria and pathogenic algae of the Republic of Palau. SPC Technical Paper 198, South Pacific Commission, Noumea, New Caledonia.

McKey D, Gaume L, Brouat C, Di Giusto B, Pascal L, Debout G, Dalecky A, Heil M (2005) The trophic structure of tropical ant–plant–herbivore interactions: community consequences and coevolutionary dynamics. In Biotic interactions in the tropics: their role in the maintenance of species diversity (eds Burslem D, Pinard M, Hartley S) pp. 386–413, Cambridge University Press, Cambridge, UK.


203

McLeod R, Reay F, Smyth J (1994) Plant nematodes of Australia listed by plant and by genus. New South Wales Agriculture, Sydney, and Rural Industries Research and Development Corporation, Canberra, Australia.

McRae W (1934) Foot-rot diseases of Piper betle L. in Bengal. Indian Journal of Agricultural Science 4: 585–617.

Merny G, Mauboussin JC (1973) Action possible des nématodes dans le rabougrissement ou ‘clump’ de l’arachide au Sénégal. Nematologica 19: 406–408.

Merrifield K (1999) Biology, host ranges, and damage levels of root-parasitic nematodes on selected central Oregon crops. Version 3. Oregon State University Nematode Testing Lab. http://www.science.oregonstate.edu/bpp/Nematodes/central_Oregon_crops.htm (accessed January 2011).

Midmore DJ, Parker J, Clark J (2005) Crop protection. An issue for the Asian vegetables, and herbs and spices industries. Rural Industries Research & Development Corporation, Publication No. 05/093, Canberra, Australia.

Midmore D, White D, Nguyen V, Hicks D, Coleman E, Newman S, Wilk P, Reeve D, McLaughlin P (2006) Development of taro, yam, yam bean and sweet potato exports to Japan and USA.. Rural Industries Research & Development Corporation, Publication No. 06/101, Canberra, Australia.

Miller D (1923) The Fiji lemon weevil. New Zealand Journal of Agriculture 26: 34–35.

Miller JH, Chamblis EB, Bargeron CT (2006) Invasive plants of the thirteen southern States. Invasive Exotic Species of North America. http://www.invasive.org/seweeds.cfm (accessed January 2011).

Mishra C, Mandal R (1989) Occurrence of Meloidogyne thamesii and Helicotylenchus mucronatus on ramie, Boehmeria nivea. Indian Journal of Nematology 18: 114.

Mitchell PL (2000) Leaf-footed bugs (Coreidae). In Heteroptera of economic importance (eds Schaefer CW, Panizzi AR) pp. 337–403. CRC Press, Boca Raton, USA.

Moran PJ, Goolsby JA (2010) Biology of the armored scale Rhizaspidiotus donacis (Hemiptera: Diaspididae), a candidate agent for biological control of giant reed. Annals of the Entomological Society of America 103: 252–263.

Moritz G, Kumm S, Mound L (2004) Tospovirus transmission depends on virus ontogeny. Virus Research 100: 143–149.

Mortimer JJ, Bridge J, Jackson GVH (1981) Hirschmanniella sp., an endoparasitic nematode associated with miti-miti disease of taro corms in the Solomon Islands. FAO Plant Protection Bulletin 29: 9–11.

Mound LA (2008) Caliothrips striatopterus (Kobus, 1893). Australian faunal directory. Australian Biological Resources Study, Canberra. http://www.environment.gov.au/biodiversity/abrs/online-resources/fauna/afd/index.html (accessed January 2011).

Muthappa BN (1987) Records of microorganisms in Papua New Guinea 1977-1986. Department of Agriculture and Livestock, Research Bulletin No. 43. Port Moresby, Papua New Guinea.

Mycobank (2011) Fungal databases. Nomenclature and species banks. Online taxonomic novelties submission. International Mycological Association. http://www.mycobank.org/DefaultPage.aspx (accessed January 2011).


204

Nafus DM (1997) An insect survey of the Federated States of Micronesia and Palau. South Pacific Commission, Noumea, New Caledonia.

Nakashima N, Noda H (1995) Nonpathogenic Nilaparvata lugens reovirus is transmitted to the brown planthopper through rice plant. Virology 207: 303–307.

Nasir YJ (1978) Araceae. Flora of Pakistan vol. 120. Agricultural Research Council, Islamabad, Pakistan.

Navarro A, Areta R, Vargo D (1986) Taro experiment: cultivar and spacing trial no. 2. Land Grant Program, Land Grant Technical Report No. 2, Pago Pago, American Samoa.

Nelson SC, Ploetz RC, Kepler AK (2006) Musa species (banana and plantain) Musaceae (banana family). Species Profiles for Pacific Island Agroforestry. http://www.agroforestry.net/tti/Musa-banana-plantain.pdf (accessed January 2011).

Nelson SC (2008) Dasheen mosaic of edible and ornamental aroids. Cooperative Extension Service PD-44. College of Tropical Agriculture and Human Resources, University of Hawaii at Mānoa. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/PD-44.pdf (accessed January 2011).

Nielsen ES, Edwards ED, Rangsi TV (1996) Checklist of the Lepidoptera of Australia. Monographs on Australian Lepidoptera 4. CSIRO Publishing, Canberra, Australia.

Nishida GM (2008) French Polynesia beetle checklist (preliminary). Version 2008 November 19. http://essigdb.berkeley.edu/checklists/fpColeoptera.doc (accessed January 2011).

Njuguna LK, Bridge J (1998) Plant parasitic nematodes of Irish potatoes (Solanum tuberosum) in Central Province and sweet potatoes (Ipomoea batatas) in Central, Nyanza and Coast Provinces of Kenya. International Journal of Nematology 8: 21–26.

Norton DC, Niblack TL (1991) Biology and Ecology of Nematodes. In Manual of agricultural nematology (Ed. Nickle WR) pp. 47–74. Marcell Dekker Inc, New York, New York, USA.

NRCS (2009) United States Department of Agriculture Natural Resources Conservation Service Plants Database. National Plant Data Center, Baton Rouge, USA. http://plants.usda.gov/ (accessed January 2011).

NTDPIF (2011) Technical Annual Report 2000/01. Technical Bulletin No. 295. Northern Territory Department of Primary Industries and Fisheries, Darwin, Australia. http://www.nt.gov.au/d/Content/File/p/AR/TB295.pdf (accessed March 2011).

NZ MAF (1999) Import health standard. Fresh fruit/vegetables. Green beans, Phaseolus spp. from South Africa. Ministry of Agriculture and Fisheries, Wellington, New Zealand. http://www.biosecurity.govt.nz/files/ihs/beans-za.pdf (accessed January 2011).

NZ MAF (2002) Import health standard. Cut flowers and branches Cordyline and Dracaena species from all countries. Ministry of Agriculture and Fisheries, Wellington, New Zealand. http://www.biosecurity.govt.nz/imports/plants/standards/cordyline-dracaena.htm (accessed January 2011).

NZ MAF (2008) Import risk analysis: fresh Citrus fruit (7 species) from Samoa (Final). Biosecurity New Zealand, Ministry of Agriculture and Forestry, Wellington, New Zealand. http://www.biosecurity.govt.nz/files/regs/imports/risk/citrus-samoa-ra.pdf (accessed January 2011).


205

Ochoa R, Vargas C, Aguilar H (1994) Phytophagous mites of Central America: an illustrated guide. Centro Agronómico Tropical de Investigación y Enseñanza, Turrialba, Costa Rica.

O’Gara FP (1998) Striking the balance. Sustainable farming and grazing systems for the semi-arid tropics of the Northern Territory. Northern Territory Department of Primary Industry and Fisheries, Berrimah, Australia. http://www.nt.gov.au/d/Primary_Industry/index.cfm?Header=Striking%20the%20Balance (accessed December 2010).

Oklahoma Department of Wildlife Conservation (2009) Noxious aquatic plants. http://www.wildlifedepartment.com/aquaticplants.htm (accessed January 2011).

Oliveira ML, Melo GL, Niella ARR, Silva VR (2008) Black root rot caused by Rosellinia pepo, a new disease of the clove tree in Brazil. Tropical Plant Pathology 33: 90–95.

Onwueme I (1999) Taro cultivation in Asia and the Pacific. Food and Agriculture Organisation of the United Nations, Regional Office for Asia & the Pacific, RAP Publication 1999/16, Bangkok, Thailand.

Onyilagha JC, Omenyi AS, Olloh HC, Lowe J (1987) Colocasia esculenta (L.) Schott, Colocasia antiquorum Schott, how many species? 1. A preliminary investigation. Euphytica 36: 687–692.

Ooka JJ (1994) Taro diseases: a guide for field identification. Pest Management Guidelines. Research extension series, University of Hawaii. http://www.extento.hawaii.edu/kbase/reports/vegetable_pest.htm (accessed January 2011).

Ooka JJ, Yamamoto B (1979) Pythium root and corm rot of Colocasia esculenta in Hawaii (abstract). Phytopathology 69: 918.

Orchard AE (2007) Infra-specific variation in Colocasia esculenta (L.) Schott (Araceae). Australian Systematic Botany Society Newsletter 129: 2–5.

Orton Willims KJ (1980) Plant parasitic nematodes of the Pacific. Technical report Vol. 8, UNDP/FAO-SPEC Survey of Agricultural Pests and Diseases in the South Pacific. Commonwealth Institute of Helminthology, St Albans, UK.

Orton Williams KJ (1985) Some Pacific Criconematina (Nemata). Records of the Australian Museum 37: 71–83.

Paiki FA (1996) Symptoms of taro leaf blight disease (Phytophthora colocasiae) and relationship with yield components in Biak, Irian Jaya. Science in New Guinea 21: 153–157.

Parkinson N, Stead D, Bew J, Heeney J, Tsror L, Elphinstone J (2009) Dickeya species relatedness and clade structure determined by comparison of recA sequences. International Journal of Systematic and Evolutionary Microbiology 59: 2388–2393.

Payan LA (1989) The intraspecific variation of Pratylenchus brachyurus. PhD thesis, University of Florida. http://www.archive.org/download/intraspecificvar00paya/intraspecificvar00paya.pdf (accessed February 2011).

Pearson MN, Jackson GVH, Sealea J, Morar SG (1999) Evidence for two rhabdoviruses in taro (Colocasia esculenta) in the Pacific region. Australasian Plant Pathology 28: 248–253.


206

Persley D, Sharman M, Thomas J, Kay I, Heisswolf S, McMichael L (2007) Thrips and tospovirus: a management guide. Cooperative Research Centre for Tropical Plant Protection. Department of Primary Industries and Fisheries, Queensland. http://www.dpi.qld.gov.au/documents/Biosecurity_GeneralPlantHealthPestsDiseaseAndWeeds/Thrips-Tospovirus-Booklet-lorez.pdf (accessed January 2011).

Phookan AK, Rachid HA, Rathaiah Y, Bhagabati KN, Roy AK (1996) Bacterial leaf blight of colocasia in Assam – A new record from India. Indian Phytopathology 49: 104–105.

Pittaway AR, Kitching IJ (2009) Theretra silhetensis silhetensis (Walker, 1856). Sphingidae of the Eastern Palaearctic species list, Natural History Museum, London. http://tpittaway.tripod.com/china/t_sil.htm (accessed January 2011).

Plant Nematode Lab Taiwan (2003a) Nematode pests with quarantine significance of Taiwan affecting major crops of the countries in Asia and the Pacific regions. http://benz.nchu.edu.tw/~tttsay/nematode/list11.htm (accessed January 2011).

Plant Nematode Lab Taiwan (2003b) Nematodes of Crops in Taiwan. http://benz.nchu.edu.tw/~tttsay/nematode/list12.htm (accessed January 2011).

Pohronezny K, Dankers W (1986) Bacterial leaf spot of Malanga (Xanthomonas caracu): a bacterial disease of potential importance to the tropical foliage industry. Proceedings of the Florida State Horticultural Society 99: 325–328.

Polinkovskii AI (1979) Species composition and geographical distribution of nematodes from the family Longidoridae (Nematoda, Dorylaimoidea) in Moldavian vineyards. Izvestiya Akademii Nauk Moldavskoi SSR, Biologicheskie i Khimicheskie Nauki 2: 37–48.

Prabha MJ (1973) Two species of Longidorus from Marathwada region. Nematologica 19: 62–68.

Purdy LH, Schmidt RA, Gramacho KP (1998) Diseases of cacao (Theobroma cacao L.). International Society for Molecular Plant-Microbe Interactions. http://www.ismpminet.org/resources/common/names/cacao.asp (accessed January 2011).

Purseglove JW (1972) Tropical crops. Monocotyledons. Longham, London, UK.

Putter CAJ (1976) The phenology and epidemiology of Phytophthora colocasiae Racib. on taro in East New Britain Province Papua New Guinea. Thesis submitted to the Faculty of Science, University of Papua New Guinea for the degree of Master of Science, December 1976. http://ecoport.org/storedReference/1425/TOC.HTM (accessed January 2011).

Queneherve P, Van den Berg E (2005) Liste des nématodes phytoparasites (Tylenchida et Dorylaimida) des départements français d’Amérique (Guadeloupe, Martinique et Guyane) et dispositions réglementaires. Liste dispositions réglementaires. OEPP/EPPO Bulletin 35: 519–530.

Quitugua RJ, Trujillo EE (1998) Survival of Phytophthora colocasiae in field soil at various temperatures and water matric potentials. Plant Disease 82: 203–207.

QUT (2003) Development and application of virus indexing protocols for the international movement of taro germplasm. Plant Technology Program, Science Research Centre, Queensland University of Technology, Australia and The Regional Germplasm Centre, Secretariat of the Pacific Community, Suva, Fiji.


207

Raabe RD, Conners IL, Martinez AP (1981) Checklist of plant diseases in Hawaii. Hawaii Institute for Tropical Agriculture and Human Resources, College of Tropical Agriculture and Human Resources, University of Hawaii, Information Text Series No. 22, Hawaii, USA.

Rachid HA, Phookan AK, Das BC (1998) Perpetuation of Xanthomonas campestris causing leaf blight of arum (Colocasia esculenta). Indian Journal of Agricultural Sciences 68: 279–280.

Rama K, Dasgupta MK (2000) Population ecology and community structure of plant parasitic nematodes associated with coconut and arecanut in northern West Bengal. Indian Journal of Nematology 30: 175–182.

Ratanaprapa D, Boonduang A (1975) Identification of plant parasitic nematodes of Thailand. A second systematic study of Hoplolaimidae in Thailand. Department of Agriculture, Plant Protection Service Technical Bulletin 27, Bangkok, Thailand.

Revill PA, Jackson GVH, Hafner GJ, Yang I, Maino MK, Dowling ML, Devitt LC, Dale JL, Harding RM (2005a) Incidence and distribution of viruses of taro (Colocasia esculenta) in Pacific Island countries. Australasian Plant Pathology 34: 327–331.

Revill PA, Trinh X, Dale J, Harding R (2005b) Taro vein chlorosis virus: characterization and variability of a new nucleorhabdovirus. Journal of General Virology 86: 491–499.

Riley IT, Kelly SJ (2002) Endoparasitic nematodes in cropping soils of Western Australia. Australian Journal of Experimental Agriculture 42: 49–56

Robbins RT, Brown DJF (1995) Amended descriptions of Longidorus sylphus Thorne, 1939, L. crassus Thorne, 1974, and L. fragilis Thorne, 1974 (Nematoda: Longidoridae). Journal of Nematology 27: 94–102.

Robène-Soustrade I, Laurent P, Gagnevin L, Jouen E, Pruvost O (2006) Specific detection of Xanthomonas axonopodis pv. dieffenbachiae in Anthurium (Anthurium andreanum) tissues by nested PCR. Applied and Environmental Microbiology 72: 1072–1078.

Rodríguez Manzano A, Rodríguez Nodals AA, Román Gutiérrez MI, Fundora Mayor Z, Castińeiras Alfonso L (2001) Morphological and isoenzyme variability of taro (Colocasia esculenta (L.) Schott) germplasm in Cuba. Plant Genetic Resources Newsletter 126: 31–40.

Rossi CE, Ferraz LCCB (2005) Plant parasitic nematodes of the superfamily Tylenchoidea associated with subtropical and temperate fruits in the States of Sao Paulo and Minas Gerais, Brazil. Nematologia Brasiliera 29: 171–182.

Rossman AY, Samuels GJ, Rogerson CT, Lowen R (1999) Genera of Bionectriaceae, Hypocreaceae and Nectriaceae (Hypocreales, Ascomycetes). Studies in Mycology 42: 1–248.

Saeed M (1974) Studies on some stylet-bearing nematodes associated with sapodilla (Achras zapot L.) with special reference to Hemicriconemodies mangiferae Siddiqi, 1961. Ph.D. thesis, Karachi University, Pakistan.

Sallam MN, Allsopp PG, Chandler KJ, Samson PR (2007) Sugarcane. In Pests of field crops and pastures. Identification and control (Ed. Bailey PT) pp. 305–342. CSIRO Publishing, Collingwood, Australia.

Sampson PJ, Walker J (1982) An annotated list of plant diseases in Tasmania. Department of Agriculture Tasmania, Australia.


208

SARE (2001) Survival of taro: agronomic and pathological research for sustainable production. Project Report 2001. Sustainable Agriculture Research and Education, Western region, Utah State University, Logan, USA.

SARE (2003) Survival of taro: agronomic and pathological research for sustainable production. Project Report 2003. Sustainable Agriculture Research and Education, Western region, Utah State University, Logan, USA. http://wsare.usu.edu/pro/pr2003/SW99-005.pdf (accessed January 2011).

Sato D (2000) Taro root aphid (Patchiella reaumuri [Kaltenbach]). Agricultural Pests of the Pacific, Agricultural Development in the American Pacific. http://www.ctahr.hawaii.edu/adap2/Publications/ADAP_pubs/2000-21.pdf (accessed January 2011).

Sato DM, Hara AH (1997) Taro Root Aphid. Insect pests, December 1997. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. http://www2.ctahr.hawaii.edu/oc/freepubs/pdf/IP-1.pdf (accessed January 2011).

Sauer JD (1993) Historical geography of crop plants: a select roster. CRC Press, Boca Raton, USA.

Sauer MR (1981) Plant nematodes associated with fruit trees in northern Australia. Australian Journal of Experimental Agriculture & Animal Husbandry 21: 129–131.

Sawada K (1959) Descriptive Catalogue of Taiwan (Formosan) Fungi, Part XI. In Special publication no. 8. (eds Imazeki R, Hiratsuka N, Asuyama H) pp. 1–268. College of Agriculture, National Taiwan University, Taipei, Taiwan.

Schliephake E (1985) Occurrence of plant parasitic nematodes in citrus plantations of central and western Cuba. Beitrage zur Tropischen Landwirtschaft und Veterinarmedizin 23: 307–314.

Seifert KA (1985) A monograph of Stilbella and some allied Hyphomycetes, Studies in Mycology 27: 1–235.

Shaw DE, Plumb RT, Jackson GVH (1979) Virus diseases of taro (Colocasia esculenta) and Xanthosoma sp. in Papua New Guinea. Papua New Guinea Agricultural Journal 30: 71–97.

Shea K (2004) Irradiation of sweetpotatoes from Hawaii. US Department of Agriculture, Animal and Plant Health Inspection Service 7 CFR Part 318 [Docket No. 03-062-2]. Federal Register Doc 04-3428. Federal Register 69: 7541–7547.

Shine C, Reaser JK, Gutierrez AT (2003) Invasive alien species in the Austral-Pacific region. National Reports and Directory of Resources, Global Invasive Species Programme: Cape Town, South Africa.

Shivas RG (1989) Fungal and bacterial diseases of plants in Western Australia. Journal of the Royal Society of Western Australia 72: 1–62.

Shivas RG, Alcorn JL (1996) A checklist of plant pathogenic and other microfungi in the rainforests of the wet tropics of northern Queensland. Australasian Plant Pathology 25: 158–173.

Siddiqi MR (1962) Studies on the genus Longidorus Micoletzky, 1922 (Nematoda: Dorylaimoidea), with descriptions of 3 new species. Proceedings of the Helminthological Society of Washington 29: 177–188.

Siddiqi MR (2000) Tylenchida. Parasites of plants and insects. 2nd Edition. CABI Publishing, Wallingford, UK.


209

Simmonds HW (1928) Entomological notes. Elytroteinus subtruncatus, Fairm. Agricultural Journal of the Department of Agriculture Fiji 1: 1.

Simmonds HW (1932) Weeds in relation to agriculture. Agricultural Journal of Fiji 5: 58–62.

Simmonds JH (1966) Host index of plant diseases in Queensland. Department of Primary Industries, Brisbane, Australia.

Simone GW, Zettler FW (2009) Dasheen mosaic disease of araceous foliage plants. Plant Pathology Fact Sheet PP-42. University of Florida. http://plantpath.ifas.ufl.edu/takextpub/Factsheets/pp0042.pdf (accessed January 2011).

Sinha S (1940) A wet rot of leaves of Colocasia antiquorum due to secondary infection of Choanephora cucurbitarum Thaxter and Choanephora trispora Thaxter sp. (=Blakeslea trispora Thaxter). Proceedings of the Indian Academy of Science, Section B 19: 167–176.

Sivanesan A, Holliday P (1998) Cochliobolus geniculatus. CMI descriptions of pathogenic fungi and bacteria. No. 727. CAB International, Wallingford, UK.

Smith AC (1979) Flora vitiensis nova. Vol. 1, pp. 456–457. Pacific Tropical Botanical Gardens, Lawai, Kauai, Hawaii, USA.

Smith KGV (1978) Some remarkable Tachinid larvae (Diptera) parasitic in species of Apirocalus Pascoe (Coleoptera: Curculionidae) in New Guinea. Journal of the Australian Entomological Society 17: 347–350.

Soltic S, Peacock L (2006) A comparison of inductive and transductive models for predicting the establishment potential of the exotic scale, Aspidiella hartii (Cockerell) in New Zealand. Bulletin of Applied Computing and Information Technology 4: 2. http://www.naccq.ac.nz/bacit/0402/2006Soltic_Cockerell.htm (accessed January 2011).

SPC (2003) Taro beetle. Secretariat of the Pacific Community. http://www.spc.int/pps/pest_of_the_month_for_december_2003.htm (accessed January 2011).

Spriggs M (2002) Taro cropping systems in the Southeast Asian-Pacific Region: an archaeological update. In Vegeculture in eastern Asia and Oceania (eds Yoshida S, Matthews PJ) JCAS Symposium Series 16, pp. 77–94. Japan Centre for Area Studies, Osaka, Japan.

Stirling GR, Blair BL, Pattemore JA, Garside AL, Bell MJ (2001) Changes in nematode populations on sugarcane following fallow, fumigation and crop rotation, and implications for the role of nematodes in yield decline. Australasian Plant Pathology 30: 323–335.

Su X, Zou F, Guo Q, Huang J, Chen TX (2001) A report on a mosquito-killing fungus, Pythium carolinianum. Fungal Diversity 7: 129–133.

Suklim K, Flick GJ, Bourne DW, Granata LA, Eifert J, Williams R, Popham D, Wittman R (2008) Microbiology, physical and sensory quality of vacuum-packaged fresh blue crab meat (Callinectes sapidus) treated with high hydrostatic pressure. Food Protection Trends 28: 96–106.

Szent-Ivany JJH, Catley A (1960) Host plant and distribution records of some insects in New Guinea and adjacent islands. Pacific Insects 2: 255–261.

Tanimoto T (1990) Distribution and morphological characteristics of wild taro (Colocasia esculenta Schott) in Japan and Taiwan. Japanese Journal of Breeding 40: 233–243.


210

TaroPest (2008) TaroPest. http://taropest.sci.qut.edu.au/ (accessed September 2008). Website no longer available.

ten Hoopen GM, Krauss U (2006) Biology and control of Rosellinia bunodes, Rosellinia necatrix and Rosellinia pepo: A review. Crop Protection 25: 89–107.

Tenbrick VL, Hara AH (1992a) Hemiberlesia lataniae (Signoret). Crop Knowledge Master, Extension Entomology & UH-CTAHR Integrated Pest Management Program. http://www.extento.hawaii.edu/kbase/Crop/Type/h_latani.htm (accessed January 2011).

Tenbrick VL, Hara AH (1992b) Pinnaspis buxi (Bouche). Crop Knowledge Master, Extension Entomology & UH-CTAHR Integrated Pest Management Program. http://www.extento.hawaii.edu/kbase/crop/Type/p_buxi.htm (accessed January 2011).

Thompson A, Johnson A (1953) A host list of plant diseases in Malaya. Mycological Papers 52: 1–38.

Thompson SA (2000) Araceae. In Flora of North America vol. 22 (eds Flora of North America Editorial Committee). Flora of North America Editorial Committee, New York, USA.

Tomlinson DL (1987) A bacterial leaf disease of taro (Colocasia esculenta) caused by Xanthomonas campestris in Papua New Guinea. Tropical Pest Management 33: 353–355.

Townshend JL (1962) The root lesion nematode Pratylenchus penetrans (Cobb, 1917) Filip. & Stek., 1941, in strawberry in the Niagara Peninsula and Norfolk County in Ontario. Canadian Journal of Plant Science 42: 728–736.

Trade Forum (2002) The Roundtable reveals the mystery behind the taro mite. Trade Forum 23: 4. http://www.southpacificbiz.net/library/docs/importexport/Trade%20Forum%20-%20Mar%20Apr%202002.pdf (accessed January 2011).

Trujillo EE (1965) The effects of humidity and temperature on Phytophthora blight of taro. Phytopathology 55: 183–188.

Trujillo EE, Menezes TD, Cavaletto CG, Shimabuku R, Fukuda SK (2002) Promising new taro cultivars with resistance to Taro leaf blight: 'Pa'lehua', 'Pa'akala', and 'Pauakea'. Cooperative Extension Service, College of Tropical Agriculture and Human Resources, New Plants for Hawaii No. 7: 1–4, Manoa, Hawaii, USA.

Tyson JL, Fullerton RA (2007) Mating types of Phytophthora colocasiae from the Pacific region, India and South-east Asia. Australasian Plant Disease Notes 2: 111–112.

Uchida JY (1998) Research updates: Taro pocket rot. Taro Festival. http://www.extento.hawaii.edu/IPM/taro/Tarorot.pdf (accessed January 2011).

Uchida JY, Silva JA, Kadooka CY (2002) Improvements in taro culture and reduction in disease levels. Cooperative Extension Service PD-22. College of Tropical Agriculture and Human Resources, University of Hawaii at Mānoa. http://www2.ctahr.hawaii.edu/oc/freepubs/pdf/PD-22.pdf (accessed January 2011).

Uchida JY, Kadooka CY, Aragaki M (2003) The relationship of Phytophthora sp. to the cause of taro pocket rot in Hawaii. American Phytopathological Society 2003 Pacific Division Meeting Abstracts. http://www.apsnet.org/members/divisions/pac/meetings/Pages/2003MeetingAbstracts.aspx (accessed January 2011).


211

Ugwuanyi JO, Obeta JAN (1996) Fungi associated with storage rots of cocoyams (Colocasia spp.) in Nsukka, Nigeria. Mycopathologia 134: 21–25.

Upsher FJ, Upsher CM (1995) Catalogue of the Australian national collection of biodeterioration microfungi. Aeronautical and Marine Research Laboratory, Defence Science and Technology Organisation, Melbourne, Australia.

Valenzuela H, Sato D (2004) Taro production guidelines for Kauai. University of Hawaii. http://www.extento.hawaii.edu/kbase/reports/taro_prod.htm (accessed January 2011).

van den Oever R, van den Berg E, Chirruco JA (1998) Plant parasitic nematodes associated with crops grown by smallholders in Mozambique. Fundamental Applied Nematology 21: 645–654.

Vargo A (2000) Taro planthopper (Tarophagus proserpina [Kirkaldy]). Agricultural Pests of the Pacific ADAP 2000-22. Agricultural Development in the American Pacific, University of Hawaii at Manoa, Honolulu, USA. http://www.ctahr.hawaii.edu/adap/Publications/ADAP_pubs/2000-22.pdf (accessed January 2011).

Vasquez EA (1990) Yield loss in taro due to Phytophthora leaf blight. Journal of Root Crops 16: 48-50.

Vauterin L, Hoste B, Kersters K, Swings J (1995) Reclassification of Xanthomonas. International Journal of Systematic Bacteriology 45: 472–489.

Vawdrey LL, Peterson RA (1990) Diseases of kenaf (Hibiscus cannabinus) in the Burdekin River Irrigation Area. Australasian Plant Pathology 19: 34–35.

Venette RC, Davis EE (2004) Mini Risk Assessment – Passionvine mealybug: Planococcus minor (Maskell) [Pseudococcidae: Hemiptera]. Animal and Plant Health Inspection Service, United States Department of Agriculture. http://www.aphis.usda.gov/plant_health/plant_pest_info/pest_detection/downloads/pra/pminorpra.pdf (accessed January 2011).

Venter C, De Waele D, Van Eeden CF (1992) Plant-parasitic nematodes on field crops in South Africa. 4. Groundnut. Fundamental Applied Nematology 15: 7–14.

Vinning G (2003) Select markets for taro, sweet potato and yam. Rural Industries Research & Development Corporation, Publication No. 03/052, Canberra, Australia.

Waller JM, Bridge J (1978) Plant diseases and nematodes in the Sultanate of Oman. Pest Articles and News Summaries (PANS) 24: 313–326.

Waterhouse DF (1997) The major invertebrate pests and weeds of agriculture and plantation forestry in the southern and western Pacific. Australian Centre for International Agricultural Research, Canberra, Australia.

Watson GW (2011) Diaspididae of the World. In Arthropods of economic significance (Ed. Ulenberg SA). http://wbd.etibioinformatics.nl/bis/diaspididae.php (accessed July 2011).

Watt JC (1986) Pacific Scarabaeidae and Elateridae (Coleoptera) of agricultural significance. Agriculture, Ecosystems and Environment 15: 175–187.

Waudo SW, Seshu-Reddy KV, Lubega MC (1998) Incidence and distribution of banana nematodes and weevils in Kenya. Discovery and Innovation 10: 164–169.


212

Weddell JA (1930) Field notes on the banana fruit-eating caterpillar (Tiracola plagiata Walk.). Queensland Agricultural Journal 33, 186–201.

Wheeler Jr AG (2001) Biology of the plant bugs (Hemiptera: Miridae): pests, predators, opportunists. Cornell University Press, Ithaca, New York, USA.

Whitehead AG (1998) Plant nematode control. CAB International, Wallingford, UK.

Whitfield AE, Ullman DE, German TL (2005) Tospovirus-thrips interactions. Annual Review of Phytopathology 43: 459–89.

Whitney LD, Bowers FAI, Takahashi M (1939) Taro varieties in Hawaii. College of Tropical Agriculture and Human Resources, University of Hawaii, Agricultural Experiment Station Bulletin No. 84, Honolulu.

Williams DJ (2005) An account of the mealybug genus Paraputo Laing (Hemiptera: Coccoidea: Pseudococcidae) in the Pacific region. Journal of Natural History 39: 3343–3358.

Williams DJ, Watson GW (1988) The scale insects of the tropical south Pacific region, Part 2, the mealybugs (Pseudococcidae). CAB International, Wallingford, UK.

Willingham SL, Pegg KG, Langdon PWB, Cooke AW, Peasley D, Mclennan R (2002) Combinations of strobilurin fungicides and acibenzolar (Bion) to reduce scab on passionfruit caused by Cladosporium oxysporum. Australasian Plant Pathology 31: 333–336.

Wilson JE, Siemonsma JS (1996) Colocasia. In Plant resources of south-east Asia No. 9. Plants yielding non-seed carbohydrates (eds Flach M, Rumawas F) pp. 68–72. Backhuys, Leiden, the Netherlands.

Wilson JW (1987) Careful storage of yams. Some basic principles to reduce loss. Agro-Facts Crops. IRETA Publication No. 15/87, IRETA Publications, Apia, Samoa. http://www.ctahr.hawaii.edu/adap/Publications/Ireta_pubs/yam_storage.pdf (accessed January 2011).

Wilson M, Evenhuis NL (2007) Checklist of Fiji Auchenorryncha and Sternorryncha. In Checklists of the terrestrial arthropods of Fiji (ed Evenhuis NL). Bishop Museum Technical Report 38. http://hbs.bishopmuseum.org/fiji/pdf/tr38(10).pdf (accessed November 2010).

Wong PTW, Mead JA, Croft MC (2002) Effect of temperature, moisture, soil type and Trichoderma species on the survival of Fusarium pseudograminearum in wheat straw. Australasian Plant Pathology 31: 253–257.

Wouts WM, Yeates GW (1994) Helicotylenchus species (Nematoda: Tylenchida) from native vegetation and undisturbed soils in New Zealand. New Zealand Journal of Zoology 21: 213–224.

WTO (1995) The WTO Agreement on the application of sanitary and phytosanitary measures (SPS Agreement) World Trade Organization, Geneva. http://www.wto.org/English/tratop_e/sps_e/spsagr_e.htm (accessed January 2011).

Xu J, Yang Y, Pu Y, Ayad WG, Eyzaguirre PB (2001) Genetic diversity in taro (Colocasia esculenta Schott, Araceae) in China: an ethnobotanical and genetic approach. Economic Botany 55: 14–31.


213

Yang IC, Hafner GJ, Revill PA, Dale JL, Harding RM (2003) Sequence diversity of South Pacific isolates of Taro bacilliform virus and the development of a PCR-based diagnostic test. Archives of Virology 148: 1957–1968.

Yoshino H (2002) Morphological and genetic variation in cultivated and wild taro. In Vegeculture in eastern Asia and Oceania (eds Y Shuji Y, PJ Matthews PJ) JCAS Symposium Series 16, pp. 95–116. Japan Center for Area Studies, Osaka, Japan.

Young JM, Dye DW, Bradbury JF, Panagopoulos CG, Robbs CF (1978) A proposed nomenclature and classification for plant pathogenic bacteria. New Zealand Journal of Agricultural Research 21: 153–77.

Yousef DM, Jacob JJS (1994) A nematode survey of vegetable crops and some orchards in the Ghor of Jordan. Nematologia Mediterranea 22: 11–15.

Zarina B (2006) Some new records of plant parasitic nematodes from Pakistan. Pakistan Journal of Nematology 24: 9–18.

Zeidan AB, Geraert E (1990) Helicotylenchus from Sudan, with descriptions of two new species (Nematoda: Tylenchida). Nematologia Mediterranea 18: 33–45.

Zettler FW, Hartman (1987) Dasheen mosaic virus as a pathogen of cultivated aroids and control of the virus by tissue culture. Plant Disease 71: 958–963.

Zettler FW, Jackson GVH, Frison EA (eds) (1989) FAO/IBPGR technical guidelines for the safe movement of edible aroid germplasm. International Board for Plant Genetic Resources, Food & Agriculture Organization of the United Nations, Rome, Italy.

Zhang Z (2003) Revision of the genus Rhizoglyphus of New Zealand and Australia. Landcare Research Contract Report: LC0203/159. Landcare Research, Lincoln, New Zealand.

Zhang Z (2004) Of mites and quarantine: a story of two crops. Te Taiao 3: 12–13. http://www.landcareresearch.co.nz/publications/newsletters/tetaiao/TeTaiaoIssue3.pdf (accessed January 2011).

Zimmerman EC (1994) Australian weevils (Coleoptera: Curculionoidea) volume 1, Orthoceri: Anthribidae to Attelabidae. The primitive weevils. CSIRO, East Melbourne, Australia.

Review of import conditions for fresh taro corms · In June 2005, Taro Growers Australia wrote to...

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