Soybean production is under tremendous threat from Fusarium species that cause sudden death syndrome (SDS) and the soybean cyst nematode (SCN). Until recently, SDS in the U.S. was thought to be caused only by the fungal pathogen Fusarium virguliforme. However, other Fusarium species can also cause SDS. Current control strategies involve the use of and moderately resistant and varieties coupled with fungicide seed treatments. Fields in Ohio, however, may show SDS symptoms even when seeds are treated with fungicide. This study has three objectives. First, the study will reveal the status of SDS causal agent(s) in Ohio, and alert stakeholders which species are involved. Second, the fungicide sensitivity of these SDS agents will be established. Third, the study will shed light on the interaction between SDS and SCN pathogens, not only as it relates to the level of severity of disease symptoms, but also in terms of genes that are differentially expressed during single and mixed infections.