Project Details:

Evaluating soybean aphid management with an expanded toolbox

Parent Project: Evaluating soybean aphid management with an expanded toolbox
Checkoff Organization:Iowa Soybean Association
Categories:Insects and pests, Education, Sustainability
Organization Project Code:
Project Year:2018
Lead Principal Investigator:Erin Hodgson (Iowa State University)
Co-Principal Investigators:
Keywords: Insecticide Resistance, Insecticides, Soybean Aphid (SA), Soybean Aphid - Monitoring

Contributing Organizations

Funding Institutions

Information and Results

Comprehensive project details are posted online for three-years only, and final reports indefinitely. For more information on this project please contact this state soybean organization.

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Final Project Results

Updated September 27, 2018:
Spring planting conditions throughout Iowa were first cold and wet, and most soybean fields were planted later to accommodate corn planting. Then May was warmer than normal and June turned exceptionally wet throughout most of Iowa. Population fluctuations between locations and years is typical soybean aphid dynamics for Iowa. Soybean aphids arrived on soybean in July, slightly behind average infestation dates. Soybean aphid colonization was initially patchy and continued to grow at a slow pace, likely due to hot evenings providing little relief to adults. Some commercial fields experienced exponential growth of soybean aphid after bloom, especially in northern Iowa. However, few fields in northwestern and northcentral counties had soybean aphid exceed the economic threshold. Some populations did persist until after seed set (R5–R6), but very quickly crashed at most locations by mid-September. When applications had sufficient coverage and applied at the labeled rate, efficacy for soybean was good (i.e., >95% knockdown within three days after application) throughout most of Iowa.

In addition to soybean aphid, Japanese beetle, bean leaf beetle and soybean gall midge were prevalent in some Iowa soybean fields. We conducted a “on the fly” efficacy evaluation at the ISU Johnson Research Farm and hope to have yield data summarized for the next reporting cycle.

I was able to complete proposed work, including research and extension related to soybean aphid management. I established a foliar insecticide efficacy evaluation at two locations in 2018 (northwest and northeast Iowa). I had 25+ treatments at each location. My extension efforts are summarized here:

View uploaded report Word file

View uploaded report 2 Word file

Treatment Recommendations. Population fluctuations between locations and years is typical soybean aphid dynamics for Iowa. Our recommendation for soybean aphid management in Iowa is to:

• Strongly consider using host plant resistance if soybean aphid populations are persistent and the seed agronomic traits are appropriate for the area. The use of a pyramided gene will result in lower CAD and reduce the need for foliar insecticides.

• Plant early if the field is in an area with persistent soybean aphid populations.

• Scout for soybean aphid, especially during R1–R5, and use a foliar insecticide if aphids exceed the economic threshold of 250 per plant.

• Use a product labeled for soybean aphid; most well-timed applications of foliar insecticides will provide yield protection if applied at the economic threshold and coverage is sufficient.

• Evaluate foliar insecticide efficacy three days after application to ensure soybean aphid populations were sufficiently reduced.

• Understand that late-season accumulation of CAD (i.e., after R5) may not impact yield like it does in early reproductive growth; a foliar insecticide applied after seed set may not be an economically profitable choice.

Project Years