Determining the Effect of Different Management Strategies on Target Spot of Soybean

We plan to evaluate the effect of row spacing (15 vs. 30 inch), soybean variety (target spot- susceptible vs. -resistant), and foliar fungicide application (non-treated vs. Headline vs. Miravis Top) on target spot in 2 x 2 x 3 factorial, replicated field research trials conducted in Alabama, Kentucky, and Tennessee. Research trials will be established in fields with a known history of target spot. Evaluations will include multiple target spot severity ratings and soybean yield. Soybean varieties that differ in their susceptibility to target spot, but that are resistant to other foliar diseases will be utilized to help reduce the influence that other diseases (such as frogeye leaf spot) may have on soybean yield. The use of Headline fungicide as a treatment in our trials, will help confirm the presence or absence of QoI fungicide-resistant strains of the target spot pathogen. Currently, the only reports of QoI fungicide-resistant strains of the target spot pathogen from soybean in the U.S. have been in Elmore and Limestone Counties in Alabama (Nunes Rondon and Lawrence, 2019).