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Soybean Aphids in Iowa – Past and Present

Soybean Aphids in Iowa – Past and Present. Marlin E. Rice Extension Entomologist Iowa State University. Acknowledgment. Extension Field Specialists-Crops Brian Lang, Decorah (northeast Iowa) Todd Vagts, Carroll (west central Iowa). Soybean Aphids in 2000 (year 1, confirmed counties).

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Soybean Aphids in Iowa – Past and Present

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  1. Soybean Aphids in Iowa – Past and Present Marlin E. Rice Extension Entomologist Iowa State University

  2. Acknowledgment • Extension Field Specialists-Crops • Brian Lang, Decorah (northeast Iowa) • Todd Vagts, Carroll (west central Iowa)

  3. Soybean Aphids in 2000(year 1, confirmed counties)

  4. Soybean Aphids in 2001(year 2, movement west, sprayed fields) 145,000 acres sprayed aphids move into western Iowa

  5. Soybean Aphids in 2002(year 3, few aphids, few sprayed fields) research plots

  6. July 14 Soybean aphids: an early warning in 2003 • Aphids in NE Iowa • June 16 = 10/plant • June 22 = 100/plant • June 30 = 315/plant • July 6 = 640/plant

  7. Treated Untreated Treated Untreated 1 mile rows with same variety planted straight through Northwest IA, August, 2003 Warrior, 15 bushels Courtesy: Jeff Ashland, Great Lakes Co-op

  8. Hancock County, IA, August 14, 2003 1 pt. Lorsban, 18 bushels

  9. Soybean Aphids in 2003(year 4, outbreak, Iowa pilots spray 734K ac.)

  10. Each day delay = 0.5 bushel

  11. Each day delay = 0.6 bushel

  12. The Des Moines RegisterAugust, 2003

  13. Soybean & Corn Yields 2003Iowa Ag Statistics, Annual Crop Summary • Soybean • 32 bushels/acre • Down 16 bushels/acre from 2002 • Reduction of 32 percent • Lowest yields since 1993 flood • Corn • 157 bushels/acre • Down 8 bushels/acre from 2002 • Reduction of 4 percent • Second highest average yield

  14. Summary • Economic damage 2 out of 4 years • Yield losses greatest in late July & early August in 2003 • “drought” may enhance aphid survival & yield impacts • 2001 NE Iowa • 2002 SW Iowa • 2003 northern 2/3 Iowa • Scouting is critical in 2004

  15. Soybean Aphid Research in Iowa Marlin E. Rice Extension Entomologist Iowa State University

  16. Acknowledgment • Extension Field Specialist-Crops • Brian Lang, Decorah • Northeast Iowa Research Farm • Ken Pecinovsky, Nashua

  17. Soybean Aphid Populations, Decorah, Iowa, 2001 – 2003 Brian Lang, Iowa State University Extension Year - Sites 2001 - 1 2002 - 1, 2, 3 2003 - 1, 2, 3 X = Peak in winged aphid activity. X 2001-1 X Approximate aphids per plant 2003-1 X X X 2003-2 X 2003-3 2002-3 X X X 2002-2 X X 2002-1

  18. 2001

  19. 11 12 Soybean Aphid Insecticide Trials 2001 Decorah, Iowa (Brian Lang, Iowa State University Extension) Plot 1, Harvested Oct. 4 Plot 2, Harvested Sept. 28 Date of insecticide applicationDate of insecticide application. July 12 July 26 July 12 & 26 July 12 July 26 July 12 & 26 Insecticide ----------- bu./acre ----------------- ------------- bu./acre ----------------- Dimethoate 28 26 29 40 40 41 Pounce28 27 32 42 41 50 Warrior25 25 34 43 41 50 Average27 26 32 42 41 47 Check21 35

  20. Soybean Aphid Research Plots 2002 & 2003 Decorah Nashua

  21. 8.5 bu. Soybean Aphid & Bean Leaf Beetle Insecticide Trial #1, Nashua Research Farm, 2003(sprayed Aug 7, bean leaf beetle = 24 per 20 sweeps, highest soybean aphid = 214/leaflet Aug 25) Bushels/acre

  22. 7.0 bu. Soybean Aphid & Bean Leaf Beetle Insecticide Trial #2, Nashua Research Farm, 2003(sprayed Aug 8, bean leaf beetle = 44 per 20 sweeps, highest soybean aphid = 69/leaflet Aug 18) Bushels/acre

  23. Insecticides & Seed Treatments on Soybean Aphid Brian Lang, ISU Extension, Decorah, IA 2003 Aphids per plant R1 R3 R5

  24. Summary • Several liquid insecticides provide good control of soybean aphids • Seed treatments offer promise of early-season suppression of soybean aphids

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