Photo – Illinois Soybean Association

When it comes to insecticide applications, it’s not always about whether they work—it’s also about their return on investment. That’s the focus of a multi-year study led by Dr. Nick Seiter and funded by the Illinois Soybean checkoff program. The research is digging into which insect pests actually impact soybean yield and quality—and if control measures like seed treatments or foliar insecticides provide a worthwhile return on investment. 

In 2024, the research team evaluated insecticide treatments across six field sites—four at university research farms, one at a community college demo farm, and one commercial field. The result? No measurable yield advantage from insecticide use, primarily because insect pressure was low across the board. 

“These results were expected,” said Seiter. “With minimal pest activity, it makes sense that insecticides didn’t improve yield.” 

It’s an important reminder for farmers weighing early-season seed treatments or automatic foliar passes: if pest pressure isn’t present or near threshold levels, the return may not be there. 

The research continues into 2025 with an even broader footprint. Seiter’s team will revisit the four original research sites and add five new on-farm trial locations, increasing the number of environments—and hopefully, insect pressure—for a clearer picture of when and where insecticide applications make sense. 

The expanded trial will include additional treatments, including a commercial-scale evaluation of insecticide seed treatments and earlier fungicide/insecticide applications timed for late vegetative to early reproductive stages (V-late/R2). 

By the end of this study, farmers will have clearer threshold recommendations for soybean insect pests and integrated pest management strategies that help them make more informed, cost-effective decisions about insecticide use. 

A full recap of year one results will be featured in the June edition of Illinois Field & Bean magazine. In the meantime, follow the latest research updates by visiting the Field Advisor Research Hub.