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Investigating fluopyram as a seed treatment against soybean cyst nematode in the presence of F. virguliforme

Mitchell Roth: Michigan State University

<div>Soybean cyst nematode (SCN) and <em>Fusarium virguliforme </em>are major threats to soybean production throughout the US and require careful management for optimal yields. Management strategies for both pathogens are similar and include using genetically resistant varieties, implementing diverse crop rotations, and using seed treatments containing a nematicide or fungicide for each pathogen, respectively. A commercial seed treatment formulation containing fluopyram, ILeVO, has been marketed against SCN. Fluopyram inhibits the enzyme succinate dehydrogenase in fungi and has shown efficacy against <em>F. virguliforme in vitro </em>and in field studies as a seed treatment. Field studies were conducted on 25 varieties across 2014-2016 in a location naturally infested with both SCN and <em>F. virguliforme</em>. Each variety was treated with a base seed treatment or the base treatment plus ILeVO. Soybean variety had the largest impact on SCN reproduction and fecundity. However, the addition of ILeVO showed a reduced number of SCN eggs and juveniles in the soil post-harvest for 19 varieties, and a reduced SCN fecundity in 13 varieties. A follow-up greenhouse study with two varieties in SCN and <em>F. virguliforme</em> infested soil also showed that ILeVO significantly reduced the number of SCN females compared to the base treatment. Quantification of SCN DNA using qPCR on greenhouse root samples showed a reduction in SCN DNA in roots containing ILeVO seed treatments compared to treatments without ILeVO.</div>