Effect of Purshade and Surround on Thrips Pressure in Hawaii Seed Corn. Lance R. Atkins M.S. Agronomy Student Iowa State University March 2016

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1 Effect of Purshade and Surround on Thrips Pressure in Hawaii Seed Corn Lance R. Atkins M.S. Agronomy Student Iowa State University March 2016

2 Introduction Raised in the Northwest, Washington and Idaho. Worked in agriculture as a teenager Received a B.S. in Agricultural Science from Brigham Young University Idaho. (BYU I) Worked for Crop Production Services from as a Crop Advisor.

3 Start of Masters Degree Started position as IPM Lead for Syngenta Seeds on Kauai, HI in August 2009 Began M.S. in Agronomy in Fall 2010

4 Seed Corn in Hawaii Most major companies are present in Hawaii Winter nurseries and year round planting conditions allow for new varieties to reach market faster. Seed industry contributes $200 million directly to Hawaii economy. More indirectly.

5 Thrips Corn thrips (Frankliniella williamsi) are a serious pest in Hawaiian seed corn. Known host for MCMV Continuous plantings allow for continuous life cycles, with no winter to limit reproduction.

6 MCMV Maize Chlorotic Mottle Virus Transmitted by thrips Can be severe in some fields to the point of achieving no yield.

7 Fine, chlorotic longitudinal yellow streaks parallel to leaf veins Yellow streaks coalesce to create chlorotic mottling Leaf necrosis, stunting, and plant death follows. Ears may be short, malformed, and partially filled. Infection can be confirmed with lab test. MCMV Symptoms

8 Integrated Approach Isolation from infected areas Fallows Workflow of people and equipment Rogueing Insecticides

9 Alternative Products Purshade (Calcium carbonate) Surround (kaolin clay) Both have been marketed as an irritant or deterrent to thrips, to be used for suppression. No data existing on actual efficacy

10 Field Experiments Treatments evaluated for thrips control on Kauai and Oahu, Hawaii 2013 Treatment Kauai Oahu Control/Check no insecticides X Control/Check No insecticides; with seed treatment a X X Conventional Insecticide program b with seed treatment a X X Conventional Insecticide program plus Surround c with seed treatment a X X Conventional Insecticide program plus Purshade d with seed treatment a X X Surround c Alone with seed treatment a X Purshade d Alone with seed treatment a X

11 Experiment Details Assessments performed 48 hours after application. Insect Counts performed by pulling whorl and counting insects. PCR tests taken by sampling 5 leaf strips within a rep. Plants for sampling designated at random prior to assessment. Planting Date Dates of Insecticide Apps Dates of assessment Kauai Oahu Mar. 26, 2013 Oct. 26, /8, 4/15, 4/23, 4/30 4/10, 4/17, 4/25, 5/1 11/6, 11/13, 11/20, 11/28 11/8, 11/15, 11/22, 11/30

12 Maize chlorotic mottle severity scale 1 = None or extremely limited streaking to one area only, no impact to plant 2 = Streaking in more than one area, but with minimal or no impact to plant 3 = Some general streaking throughout plant, with minimal impact to plant 4 = General streaking throughout plant, noticeable impact to plant 5 = Evident damage and suffering from thrip streaking, chlorotic plant

13 Conditions Kauai Normal weather: limited rainfall, trade winds (west) Planted just 5 feet downwind from many nursery blocks, which had been continuously planted for previous 8 weeks. Thrips populations and MCMV incidence rate were extremely high. Oahu Normal weather Planted between two parent seed increase fields. (approx. 330 feet away) Thrips populations very low at time of planting MCMV present in neighboring fields, but very low.

14 Initial Observations on Kauai Check without seed treatment had highest insect counts, and most severe MCMV symptoms. Purshade alone and Surround alone had more insects, more severe MCMV symptoms than when used in combination with an insecticide (P<0.1) Therefore these 3 treatments were dropped for the subsequent Oahu trial

15 Cumulative Thrips Days Treatment Seed treated but not sprayed Conventional Insecticide Insecticide + Purshade Insecticide + Surround Kauai Trial: LSD = 73.1 Oahu Trial: LSD = 52.7 t t N CTD N CTD Grouping Grouping A A B B B B B B

16 Cumulative Thrips Days Conventional insecticide treatments (with or without Purshade/Surround) had lower CTD than nonsprayed check. No significant difference between conventional insecticide alone vs w/purshade or Surround.

17 Maize chlorotic mottle severity Kauai Treatment Asses. 1 Asses. 2 Asses. 3 Asses. 4 Not seed treated, not sprayed Seed treated but not sprayed Conventional Insecticide Insecticide + Purshsade Insecticide + Surround Purshade alone Surround alone Least Significant Difference

18 Maize chlorotic mottle severity Oahu Treatment Asses. 1 Asses. 2 Asses. 3 Asses. 4 Seed treated but not sprayed Conventional Insecticide Insecticide + Purshade Insecticide + Surround Least Significant Difference

19 Maize chlorotic mottle severity No difference in 5 of 8 assessments of conventional insecticide alone vs insecticide + Purshade or Surround. More severe on treatments without insecticide.

20 Cumulative Planthoppers Days Kauai Trial: LSD = 46.5 Treatment t Grouping N CPD Not treated not sprayed A Seed treated but not sprayed B Conventional Insecticide D Insecticide + Purshade D Insecticide + Surround D Purshade alone C Surround alone BC

21 Cumulative Planthoppers Days Treatments with insecticide provided better control of planthoppers on Kauai. However no statistical difference among insecticide treatments. No planthoppers in Oahu trial

22 PCR Testing Prevalence of MCMV on Kauai was high, and all reps tested positive for MCMV. Severity of maize chlorotic mottling varied between treatments: some registering 100, others registering <100,000. But no consistent patterns among treatments. MCMV prevalence was very low in Oahu and no PCR tests were positive.

23 Conclusions Adding Purshade or Surround to the standard spray program did not improve control of thrips or planthoppers.. Seed treatment works! Spraying conventional insecticide reduced insect populations vs no insecticide In high virus situations, no conventional insecticide program prevented infection by MCMV. Best management practices must continue to be followed, in particular fallows and isolation.

24 Best vs Worst Conventional Insecticide No Spray and No Seed Treat

25 Insecticide vs Insecticide+Purshade Insecticide Only Insecticide + Purshade

26 Insecticide vs Insecticide + Surround Insecticide Only Insecticide + Surround

27 Severely Affected Field from MCMV

28 Acknowledgements Syngenta Seeds Paul Russell, Steve Kai, Liko Nakaahiki, Mike Girod,Grant Manning, Kori Sakahashi, Alyssa Williams Dr. Alison Robertson ISU Staff Melissa Atkins

29 Agronomy Program through Iowa State was an immense benefit to my career. Currently work at Syngenta as the Production and Processing Manager for Sunflower in Glenn, CA. Closing

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31 Questions?