P-107 - Impact of Temperature on Cotton Seedling Disease, Root-Associated Fungal Communities, and Their Interaction with Treated Seed

Cotton seedling diseases affect stand establishment, impacting germination and early growth. Fungicide seed treatments can help reduce disease severity and improve stands. In the U.S., cotton is grown in regions with fluctuating temperatures, where cooler conditions favor seedling diseases, stressing the need for effective management strategies. The objectives of this study were to evaluate seed treatment performance under different temperatures, assessing their effect on seedling cold stress tolerance in early planting, and investigating impact on soil and root fungal communities and their interaction with cotton-treated seeds. A bioassay under controlled conditions using soil collected from two locations in Arkansas was conducted to evaluate the effect of two temperatures, 18 and 25°C, on seed germination. Treatments included no fungicide (T1), metalaxyl (T2), penflufen (T3), and a mix of prothioconazole, myclobutanil, penflufen, and metalaxyl (T4). A combination of culturing methods and metabarcoding approaches were used to assess fungal diversity. Our results suggest that the fungicide seed treatments did not significantly accelerate germination at lower temperatures but appeared to support seedlings over time, with treatments 2 and 4 showing better performance. Additionally, the different active ingredients effectively limited target fungi to low levels at both temperatures and impacted the composition of fungal communities associated with roots. Understanding temperature impact is crucial for optimizing seed treatment strategies for different environmental conditions.