P-148 - Influence of Cropping Systems on Sudden Death Syndrome of Soybean

Sudden death syndrome (SDS), primarily caused by Fusarium virguliforme, poses a significant threat to soybean production across 16 U.S. states and Ontario, Canada. SDS is favored by cool, wet soils, with rainfall after planting often intensifying symptoms. In the absence of management options after planting, growers rely on resistant cultivars, seed treatments, and adjustments to cropping systems for management. This study evaluated the impact of row spacings, plant populations, and variety selection on SDS in Kansas and Iowa. Field trials were conducted in 2023 and 2024 at two locations in Kansas locations and one in Iowa. Resistant and susceptible soybean cultivars were planted at populations of 80,000, 120,000, 160,000, and 200,000 seeds per acre. Kansas trials included 15- and 30-inch row spacings, while Iowa used 30-inch spacing only. To promote disease pressure, Kansas plots were inoculated with F. virguliforme and irrigated, while Iowa plots relied on natural SDS pressure and were not irrigated. Data collection included live plant counts, root rot severity, foliar SDS symptoms, and yield. In Kansas, resistant cultivars with 30-inch row spacing reduced foliar SDS symptoms and improved yield, though neither factor affected root rot severity. Higher plant populations increased root rot. In Iowa, cultivar selection significantly impacted SDS index and yield in 2024, while in 2023, only plant population influenced yield. No interactions were observed between cultivar and plant population These findings aid in optimizing SDS management recommendations across environments.