Key Points:
- Wet and hot weather during harvest can increase soybean seed damage and dockage
- Mid-season pesticide applications generally do not reduce late season seed damage
- Multiple fungicide applications can reduce purple seed stain, but only by 0.5%
Changes in Soybean Seed Quality
Late-season soybean seed damage is on the rise as the weather becomes increasingly wet and hot during harvest. Seed damage often results in dockage at the elevator. Farmers want to know if mid-season fungicide and insecticide applications can help minimize soybean seed quality issues at the end of the season. Science for Success researchers in North Carolina set up a multi-site study to find out.
Impact of Pesticide Application
Researchers deployed different mid-season pest management strategies across six North Carolina locations with multiple planting dates and soybean maturity groups within each location (O’Reilly et al., 2024). Pesticide management strategies were compared over 150 times and included fungicide alone at early pod development (R3), insecticide alone at R3, fungicide alone at R3 and early seed (R5), and fungicide and insecticide applied together at R3 and R5. These were compared to a non-treated control.
Researchers used the same soybean grading standards used by the federal government at grain elevators across the nation. The study found that mid-season pesticide applications did not reduce soybean seed damage. However, multiple fungicide/insecticide applications did reduce purple seed stain, but only by 0.5%. Stink bugs can cause seed damage that is graded independently and therefore should be scouted and managed.
Researchers conclude that factors like planting date, maturity group, and weather are much stronger predictors of when soybean seed damage issues will arise than mid-season pest management.
Author
Rachel Vann, University of Illinois Urbana-Champaign
References
O’Reilly, K., Vann, R. A., Collins, G. D., Lux, L. R., Stokes, D. R., & Reisig, D. D. (2025). Mid-season pest management implications for protecting soybean seed quality in North Carolina. Agronomy Journal, 117(2). https://doi.org/10.1002/agj2.70033
