Investigation of Seed Treatment and Planting Date on Alabama Soybeans

Abstract

Soybean (Glycine max L.) production in the southeastern United States is heavily influenced by interactions between insect pest pressure, agronomic practices, and environmental variability. Production practices such as planting date, threshold-based insecticide applications, and the use of seed treatments are commonly implemented to protect yield. However, effectiveness and economic return vary across production regions. Two field experiments were conducted across multiple environments in Alabama during the 2024 and 2025 growing seasons. The first evaluated the effects of fungicide and insecticide seed treatments on early-season insect pests, stand establishment, yield, and return on investment on six Alabama Agricultural Experiment Stations throughout the state. Across locations and years, seed treatments had limited effects on early-season insect pests, stand establishment, and yield. Economic benefits were inconsistent and primarily dependent on yield environment, with high yielding environments in mid-May planting dates producing the highest yield and economic return. The second experiment evaluated the effects of planting date and threshold-based insect management on insect pest populations and soybean yield in Prattville, AL. Planting date significantly influenced insect pressure, particularly for redbanded stink bug (Piezodorus guildinii) and kudzu bug (Megacopta cribraria). Threshold-based insecticide applications significantly reduced key pests and resulted in higher yields compared to non-treated plots. Soybeans planted in mid-May consistently produced higher yield and economic return across the state of Alabama. This research suggests that planting date is a primary factor in both insect pressure and soybean yield in Alabama production systems, while benefits of seed treatments are often inconsistent and site-specific.