Fusarium virguliforme, the causal agent of soybean sudden death syndrome (SDS), and Heterodera glycines, soybean cyst nematode (SCN), are two of the most important pathogens of soybean. Host resistance is currently the main management strategy for both pathogens, and there are few other options available for each pathogen. Seed treatments are now an option for farmers for use of pesticides in early plant development. Bayer CropScience recently registered a seed treatment, ILeVO® (fluopyram), with reported activity against both SDS and SCN. The research described in the following manuscript tested ILeVO® in different combinations with currently available seed treatment products for management of each pathogen separately and together. All experiments were performed in temperature-controlled water baths in the greenhouse.

The first experiment evaluated seed treatments on soybean seedlings infected with SCN alone. Plants were grown for 30 days at 27˚C. The experiment was run three times and the data were combined for analysis. Results for this experiment were somewhat unclear. However, plants treated with a seed treatment combination of Trilex® + Allegiance® + Poncho/VOTiVO® + ILeVO® had less SCN females per gram of root when compared to the same combination without ILeVO®.

The second experiment examined the effects of ILeVO® on soybeans inoculated with F. virguliforme and F. virguliforme combined with SCN. For this experiment, water baths were maintained at 24˚C and plants were allowed to grow for 35 days. Three runs of this experiment were conducted, but the data from each run was analyzed separately due to changes in experimental design. No significant differences were found among the seed treatments in any of the three runs for SDS foliar symptom severity. SDS root rot severity was significantly lower for Trilex® + Allegiance® + ILeVO® compared to Trilex® + Allegiance® in one of the three experimental runs. When looking at SDS and SCN in combination, there were significantly fewer SCN females per gram of root in the presence of ILeVO® for the contrast involving Trilex® + Allegiance® + Poncho/VOTiVO® and Trilex® + Allegiance® + Poncho/VOTiVO® + ILeVO® for the first run of the experiment. There were also significantly fewer SCN females per gram of wet root mass for the contrast of Trilex®+Allegiance®+ILeVO® compared to Trilex® + Allegiance® in the third run. These results indicate that ILeVO® may negatively affect SCN, but we detected no such negative effects of ILeVO® on SDS foliar disease symptoms in our greenhouse experiments.