Silverleaf Whitefly (SLW): Threats and management issues ... Silverleaf Whitefly (SLW): Threats and

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Transcript of Silverleaf Whitefly (SLW): Threats and management issues ... Silverleaf Whitefly (SLW): Threats and

  • D P

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    Silverleaf Whitefly (SLW): Threats and management

    issues for broad-acre crops

    Richard Sequeira – QDPI Entomology, Emerald

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    Acknowledgments

    Dr. Paul De Barro – CSIRO

    Dr. Peter Ellsworth – University of Arizona

    Mr. David Kelly – QDPI, Emerald

    Dr. Ali Duale – QDPI Entomology

    Ms Alison Shields – QDPI Entomology

    Mr. Andrew Moore – QDPI Entomology

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    Presentation Overview

    The Problem & Summary

    Basic aspects of the problem

    What you can do about it

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    The Threat: Many field crops under threat of elimination due to SLW

    – soybean, peanut, sunflower, navy bean, adzuki bean

    What Can You Do About It? • Choice of right crop for the right area

    • Choice of right crop variety

    • Where to plant it (location)

    • When to plant it (time of year)

    • What chemicals to use - Give nature a helping hand

    Summary & Take Home Message

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    Distribution • Distributed world-wide • Major pest since early 1980s

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    Distribution & History in Australia

    •Introduced to Australia in the early 90s

    •First identified by Robin Gunning of NSW Ag. as SLW

    •Rapidly spread along the Qld & northern NSW coast

    •Endemic in coastal horticultural areas

    •First discovered in Emerald in 1996

    •First major outbreak in cotton in Emerald 2001-02 season

    •Now in all major valleys in c/s Qld and n/ NSW

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    SLW: Identification Eggs

    Adult 0.8-1.2 mm

    Large nymphs 0.6 mm

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    SLW Life Cycle

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    SLW: Why Is It a Serious Pest? • Wide host range, > 500 plant species

    Sesame

    Soybean

    Weeds – native Rosella

    Cotton

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    SLW: Why Is It a Serious Pest?

    • High reproductive capacity, > 300 eggs

    Nymphs and adults on lablab

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    SLW: Why Is It a Serious Pest? • Short life cycle, egg to adult in 3 weeks

    • Acquires resistance quickly, 2-3 cycles High levels of resistance to Pyrethroids, OPs, Carbamates

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    SLW: Why Is It a Serious Pest?

    • Capable of reaching outbreak population densities very rapidly

    MANAGEMENT

    SYSTEM

    CLIMATE After P. De Barro, CSIRO

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    Management Practices Can Cause SLW Outbreaks

    • Use of broad-spectrum insecticides

    (Ops, Carbamates, Pyrethroids)

    • Poor farm hygiene:

    Crop residues and abandoned crops

    Broadleaved weed hosts in-field

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    Production System Can Facilitate SLW Outbreaks

    Emerald and surrounding areas Crop Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov

    Sorghum Cotton Peanuts D/L Cotton Sorghum (late) Soybeans D/L Sorghum Mungbeans Pumpkins Rockmelons Watermelons D/L Sunflower D/L Pulses Corn Navy Beans Wheat Chickpeas

    Planting Flowering Harvesting

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    Climate Can Facilitate SLW Outbreaks Numbers of generations for silverleaf whitefly across a range of locations.

    Location

    Generations1 Oct – Mar*

    Mar – Oct ** Mar –Dec***

    Generations per Year

    Longest Generation (days, approx)

    Narrabri* 4-7 (6) 6-9 (8) 122 days 15 Apr - 15 Aug

    Goondiwindi* 5-8 (6) 7-10 (8) 118 days 15 May - 10 Sept

    St George* 5-8 (7) 7-11 (9) 102 days 1 Jun - 10 Sept

    Biloela* 6-8 (7) 7-11 (9) 92 days 1 Jun - 1 Sept

    Emerald* 6-8 (7) 9-12 (10) 77 days 15 May - 1 Aug

    Richmond** 6-8 (7) 11-15 (13) 61 days 15 May - 15 Jul

    Katherine** 7-9 (8) 13-17 (15) 30 days 15 Jun - 15 Jul

    Kununurra** 8-10 (9) 14-18 (16) 30 days 15 Jun - 15 Jul

    Broome** 9-10 (9) 14-18 (16) 30 days 15 Jun - 15 Jul

    Bundaberg*** 5-7 (6) 7-11 (9) 87 days 1 Jul – 25 Sept

    Bowen*** 7-11 (9) 10-14 (12) 45 days 1 Jun – 15 Jul

    Ayr*** 7-11 (9) 10-14 (12) 45 days 1 Jun – 15 Jul

    Gatton*** 4-7 (5) 6-10 (8) 108 days 15 May – 1 Sept 1 Generations from 1st of the month to 1st of the month. (After P. De Barro, CSIRO)

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    SLW Risk Assessment for Broad-acre Crops

    Seasonal Risk Level Region Crop Crop Risk Winter Oct Nov Dec Jan Feb Mar Apr

    CQ Soybean VH X X XX XX XXX XXX XX Peanuts M-H XX XX XX Navy M? XX XX Sunfl M-L X X Mungs L-M X X X X X XX XX Q Coast Soybean VH X X X XX XX XXX XXX XX Peanuts M-H X X X X X XX XX XX Mungs L-M X X X X X XX XX XX Burnett Soybean H X X XX XXX XX Peanuts M X X XX XX XX Navy M? X X X X X XX XX Mungs L-M X X X X X XX XX Sunfl M-L XX XX X SQ/DD Soybean M X X XX XX X Mungs L-M X X X XX X X Sunfl M-l X X XX XX X X Navy M-L? X XX XX X NSW-NR Soybean H X XX XXX XXX XX Azuki H X XX XX X Lucerne H X X X X X X X S/Legs H X X X X X

    Risk Rating; X - Low, XX - Medium, XXX - High

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    SLW Management… …depends on 3 basic keys

    • Proper sampling Thresholds for each crop Which part of the plant to sample How frequently to sample

    No protocols developed to date On-going research on susceptibility and

    management of grain and pulse crops

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    SLW Management… …depends on 3 basic keys

    • Effective chemical use What is NOT effective? Pyrethroids, Ops, Carbamates

    What is effective? IGRs, neonicotinoids (acetamiprid, thiomethoxam),

    diafenthiuron

    Bio-rationals (oils, soaps) – calendar spraying

    What can you afford to use? Proper coverage is essential

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    SLW Management… …depends on 3 basic keys

    • Avoidance

    • Do not plant when other host crops in the area are finishing

    • Do not plant adjacent to cucurbits, sweet potato and other good host crops

    • Varietal differences within a crop – some more susceptible than others

    University of Arizona

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    Give Nature a Helping Hand

    Parasitic wasps

    Encarsia Eretmocerus

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    Give Nature a Helping Hand Mean number of large nymphs on sow thistle 2001 vs 2002

    0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

    NE NW SE SW Foley Rd

    District

    M ea

    n ny

    m ph

    s/ cm

    2

    2001 2002

    Source: Paul De Barro, CSIRO

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    Give Nature a Helping Hand SLW nymphs on cotton 2001-02 versus 2002-03

    0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

    O ct

    _0 1

    N ov

    _0 1

    D ec

    _0 1

    Ja n_

    02

    M ar

    _0 2

    O ct

    _0 2

    N ov

    _0 2

    D ec

    _0 2

    Ja n_

    03 M ea

    n (lo

    g X

    + 1)

    n ym

    ph s

    / c m

    s q

    Source: Paul De Barro, CSIRO

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    Give Nature a Helping Hand SLW: Parasitism Levels in Cotton

    0

    20

    40

    60

    80

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    Morowitz Tessman Sullivan EAC Barsby Oregan Walters

    EFE Foley Rd FSE NE NW SE SW

    % P

    ar as

    iti sm

    17/12/2002 23/01/2003

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    What lies ahead? Is SLW here to stay? More than likely

    Will it be a problem everywhere, every year? In some years, some spots

    Given the current levels of natural mortality – annual problems unlikely, unless flared by local practices

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    Conclusions SLW can be managed effectively by making

    well informed choices • Choice of right crop for the right area

    • Choice of right crop variety

    • Where to plant it (location)