Issue number: 20Date: 26/09/2014

PestFaxPestFax is a weekly informative and interactive reporting service, providing risk alerts, current information and advice on pests and diseases threatening crops and pastures throughout the grain

belt of Western Australia (WA). PestFax is supported by the Grains Research and Development Corporation (GRDC) and promotes national pest management information and Integrated Pest Management (IPM) principals.

Newsletter of the Department of Agriculture and Food, Western Australia (DAFWA).

ContentsNative budworm Black ‘sooty’ head mould on wheatCharcoal rot in lupinsAphids

To view a map of pest and disease reports, see PestFax Map and PestFax newsletters for back copies of PestFax. If you have recently observed or heard news of insect or disease pests in crops and pastures contact PestFax@agric.wa.gov.au or use the online ‘make an on-line report’ link.

Native budwormNative budworm moths have continued to be found in moderate to high numbers in locations where volunteer farmers are recording pheromone trap results on their properties. Moths are generally travelling in westerly and SW directions from their initial eastern and northern areas of origin. Moth numbers significantly increased this week on properties that previously recorded low numbers over the last six weeks. These areas include N. Cuballing (107 moths), E. Pingrup (61), S. Pingrup (156), Narrogin (22) and SW Kojonup (34). For the locations of budworm moth numbers caught in pheromone traps in recent weeks refer to: Native Budworm Moth Trap Numbers 2014.

Matt Willis (Elders) sweep netted a canola crop near Cowcowing 24 days after spraying and found two grubs (5–10 millimetres (mm)) per 10 sweeps. Prior to the spray the budworm numbers

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were recorded at 35 grubs per 10 sweeps. Another canola crop near Mollerin was sweep netted 27 days post spraying, no budworm caterpillars were found in the crop.

Caterpillars eat increasing quantities of seed and plant material as they grow with the last two growths stages (5th and 6th instar, >30mm) responsible for eating over 90% of their total grain consumption. Late season caterpillar hatchings are often too late to cause much damage if numbers are close to threshold spray levels as the grubs are very small (less than 5mm) and cause low level damage compared to larger grubs in the time remaining before pods become dry and hard. However high numbers of small caterpillars (more than 10 per 10 sweeps) will cause economic damage to canola late in the season, especially if rain prolongs crop maturity or delays swathing/desiccation.Threshold numbers for the control of native budworm on lupin and canola crops are much higher than for the more vulnerable pulse crops such as field pea and chickpeas. This is because the caterpillars do not commence to feed on lupin and canola pods until leaf drop has commenced and crops are in late maturity. Typically there is a 2–3 week window between these crops becoming susceptible to damage and when they are hard ripe and safe from feeding damage. This risk period can be longer, especially in southern areas if cooler weather prevails or late rain occurs to delay maturity.

Canola, field peas, other pulse crops, serradella and other aerially seeded pastures will all be susceptible to damage from any sized caterpillars, with larger sized caterpillars causing the most damage. However, lupin crops do not become vulnerable to damage from native budworm unless caterpillars are larger than 15mm long and crops have commenced leaf drop and colour change of pods.

Late maturing crops should be re-checked to confirm the absence of the pest. Farmers with caterpillars in their crops need to be mindful of insecticide withholding periods (WHP) close to harvest and remember that windrowing is classified as harvest.

Alpha-cypermethrin has a 21 day WHP on canola whilst others chemicals such as gamma-cyhalothin (e.g. Trojan®) has a seven day WHP on canola.

Table 1 Withholding periods in days for harvest/swathing; registered insecticides for native budworm.

Active ingredient (trade names) Canola Lupins Field peasAlphacypermethrin (e.g. Dominex®, Fastac®) 21 28 28Betacyfluthrin (Bulldock®) 14 14 7Cypermethrin (e.g. Scud®) 21 28 28Deltamethrin (e.g. Decis®) 7 7 7Esfenvalerate (Sumi-alphaflex®) 14 14 14Gamma-cyhalothrin (Trojan®) 7 14 7Lambda-cyhalothrin (e.g. Karate®) 7 14 7Methomyl (e.g. Lannate®) 7 7 7

Emamectin Not registered 21 21

Btk 0 0 0NPV 0 0 0

For further information on native budworm see the webpage: Management and economic thresholds for native budworm. Pesticide options for the control of native budworm can be found in the Winter/Spring Insecticide Spray Chart 2014 .

Black ‘sooty’ head mould on wheatPlant pathologist Ciara Beard (DAFWA) has received samples of wheat heads that have black sooty mould on them from research trials at Mullewa. Paul Bartlett (DAFWA) who collected the

samples found the symptoms on a range of varieties, particularly on heads that haven’t filled due to moisture stress earlier in the season.

Affected heads show black discoloration which gives them a very weathered appearance (see Figure 1). Ciara said that wet, humid weather during the later stages of grain development and crop maturation can be favourable for the parasitic and saprophytic fungi species that cause the mould (fungal species that cause black head mould includes Cladosporium, Alternaria, Stemphyllium and Epicoccum). Mould fungi development is particularly prevalent on heads that are prematurely ripened or undersized such as in crops that have been deficient in nutrients, lodged, or damaged by insects or other diseases, or moisture stressed during the season.

Although it has a horrible appearance, black sooty mould often only affects the tissue surrounding the grain, but not the grain itself. On its own it may not significantly affect crop yield or quality. If however, wet weather continues and harvest is delayed, the mould fungi may colonize the grain causing small dark brown, black or grey discolouration and this is often associated with grain shriveling.

Figure 1 Black sooty mould on wheat heads

Charcoal rot in lupinsRob Campbell (Landmark) reports seeing a lupin crop near Mingenew with patches of the crop drying off and dying prematurely. When the roots or crowns of affected plants are snapped a grey discolouration can be seen within the stem, generally occurring just below the soil surface. Rob estimated that 10-30% of the crop is affected by the symptoms.

Lupin crops with similar symptoms have been reported by Alana Hartley (Landmark) at East Buntine, a grower near Arrino and Leigh Smith (DAFWA) near Wongan Hills.

The crops are at the pod ripening growth stage with good main stem pod set, however yield in affected plants will be severely compromised. Plant Pathologists Geoff Thomas and Ravjit Khangura have examined the plants and confirm presence of distinctive stem symptoms of charcoal rot.

Charcoal rot is caused by Macrophomina phaseolina, which is a widespread soil-borne fungus but usually a weak pathogen. It attacks plants that are moisture-stressed when soil temperatures are warm. The stem and taproot near the soil surface become infected and when split open have the distinctive ash-grey discolouration, partly caused by masses of tiny black microsclerotia embedded in the tissue.

Often charcoal rot has only a minor effect on yield as infection takes place after the plant has completed pod set and the crop is approaching maturity. However this season infection appears to

have taken place earlier placing stress on the plants during pod set and pod ripening, bringing on premature senescence similar to drought affected plants. It is probable that the dry and warm conditions through August have provided favourable conditions for the disease to flourish.

Generally this disease is sporadic and causes limited damage and no specific management approaches are required. Rotation with non-host crops should reduce the concentration of soil borne inoculum, cereal species such as wheat and barley are not normally infected.

To monitor the scope of the disease this season, Geoff would like to hear of any further affected crops and receive samples. Simply send 4-5 affected stem bases (snap off tops) and address the sample to: Attention: Geoff Thomas, Locked bag No. 4, Bentley Delivery Centre, 6983 or drop the sample off at your local DAFWA office.

AphidsBrent Pritchard (Farmanco) reports that there are low levels of aphids present on cereal and canola crops though out the Great Southern. Monitoring will continue in these crops to pick up any population increases, but it is likely they will not reach damaging levels as Brent has observed natural bio-control agents, such as parasitised aphids and fungal diseases on some aphids.

For further information visit the webpages: Diagnosing cereal aphids, Aphid feeding damage to cereal crops, Aphid management in canola crops and the Winter/Spring Insecticide Spray Chart 2014 . For some of the beneficial insects likely to be encountered in broadacre crops and pastures, view the GRDC Back Pocket Guide Beneficial Insects.

Also available:List of registered insecticides A list of registered insecticides to control winter/spring pests on canola, lupins, cereals, field peas and pastures is available on the PestFax webpage: Winter/Spring Insecticide Spray Chart 2014

A list of registered insecticides to control autumn/winter pests on canola, lupins and cereals is available on the PestFax webpage: Autumn Winter Insecticide Guide 2014

Crop insects: the ute guide This book covers crop pests, beneficial insects, biological control, grain storage pests and biosecurity pest threats specific to WA. Copies are available from some DAFWA offices for a cost of $10.00 or by mail order by phoning the DAFWA South Perth office on +61 (0)8 9368 3710.

Free insect identification Having troubles identifying mites or other pests? For free identification, send your digital pictures (in focus) or live specimens (in a non-crushable plastic jar) to Peter Mangano or Svetlana Micic at the postal details below.

Svet Micic, DAFWA Albany 444 Albany Highway, Albany WA 6330Email: svetlana.micic@agric.wa.gov.au Phone: +61 (0)8 9892 8591 or +61 (0)427 772 051

Peter Mangano, DAFWA South Perth3 Baron-Hay Court,South Perth WA 6151Email: pmangano@agric.wa.gov.au Phone: +61 (0)8 9368 3753 or +61 (0)404 819 534

Integrated Pest Management Guidelines for grains

AgTactics and AgMemo Other regional DAFWA news updates are available on DAFWA website .

Seasonal climate outlook Seasonal climate outlooks are available on DAFWA website .

AGWEST Plant Labs Plant disease diagnostic services are located at the DAFWA South Perth office. For information on sending samples and charges contact +61 (0)8 9368 3721 or Fax +61 (0)8 9474 2658 or visit the DAFWA website or the AGWEST Plant Laboratories

Next issue of PestFax – 03 October 2014

Important disclaimer

The Chief Executive Officer of the Department of Agriculture and Food and the State of Western Australia accept no liability whatsoever by reason of negligence or otherwise arising from the use or release of this information or any part of it.

Copyright © Western Australian Agriculture Authority, 2014