P-207 - Comparison of planting dates and seed treatments on soybean in Indiana.

Soybean (Glycine max) is one of the most economically significant crops in the U.S. Grower interest has increased in planting soybeans a month earlier than normal for reasons that include time management, potential for higher yields, and soybeans having a greater tolerance to cold soils verses corn. The question then, is will extending the soybean growing season by a month will increase the risk of seedling disease and require changes in disease management? The aim of this research was to evaluate how planting date and seed treatment influence seedling disease, root rot and yield. Field trials were conducted in 2023 and 2024 at three locations in Indiana. The experiments were a split-plot design with four replications. The main plot factor was planting date (mid-April, late-April, mid-May and late-May), and the subplot factor was seed treatments that included: nontreated control; thiamethoxam + mefenoxam + picarbutrazox + fludioxonil + sedaxane; thiamethoxam; and mefenoxam + picarbutrazox + fludioxonil + sedaxane. In 2023, two of the three locations showed an increased root rot in the April planting dates, with the greatest root rot at the earliest planting date. However, there were no significant differences between planting dates for root rot at the third location. In 2024, root rot severity was greatest at the earliest planting date at all locations. While soybean yield was greatest in the two early planting dates for all site-years. Additionally, seed treatments had no statistically significant effect on disease severity or soybean yield for all site-years.