Management of Soybean Sudden Death Syndrome with Seed Treatments in Northern U.S. Field and Greenhouse Environments

Sudden death syndrome (SDS) of soybean, caused by Fusarium virguliforme, can significantly reduce soybean yield and is spreading in North America. Soybean cultivars with partial resistance are important for managing SDS, and seed treatments have been developed to supplement resistance and manage SDS where resistance is unavailable. Studies were conducted from 2020 to 2022 at two field locations in Minnesota to evaluate seed treatments containing fluopyram and pydiflumetofen and a biological seed treatment containing saponin extract from Chenopodium quinoa for managing SDS. Both locations had low soybean cyst nematode populations. The average SDS foliar disease index (FDX) severity was 50 and 19% in the untreated plots at the Rosemount and Waseca, Minnesota, field locations, respectively. Pydiflumetofen and fluopyram treatments significantly reduced FDX compared with untreated controls on susceptible and partially resistant soybean cultivars and at each field location. Pydiflumetofen significantly reduced FDX in 75% and fluopyram in 62% of the studies by cultivar. Yield was significantly greater with pydiflumetofen than with other treatments for both cultivars and significantly greater with fluopyram for one cultivar in Rosemount, where SDS severity was the greatest. None of the treatments provided a significant yield benefit in Waseca, where SDS levels were moderately low. Neither seed treatment nor cultivar significantly influenced plant population. In greenhouse experiments with the same treatments, fluopyram, pydiflumetofen, and saponin extract significantly reduced SDS development compared with controls. In summary, seed treatments can be effective for managing soybean SDS across a range of northern field and greenhouse environments with low soybean cyst nematode populations.