Agronomic and efficacy evaluations of oxathiapiprolin as a soybean seed treatment

Abstract

Phytophthora root and stem rot is a devastating disease of soybean [Glycine max (L.) Merr.] that occurs annually in North America. Plant death and severe yield loss can transpire when conditions are favorable for pathogen development. The first objective was to determine the efficacy of oxathiapiprolin as a soybean seed treatment using laboratory inoculum layer assays with different races of Phytophthora sojae. The second objective was to evaluate oxathiapiprolin seed treatments in wide area agronomic field testing using unmanned aerial vehicle (UAV) image-to-data analysis to quantify emergence, vigor, and greenness traits. The final objective was to examine the yield potential of seed treatments with oxathiapiprolin. Using inoculum layer efficacy testing in a growth chamber with P. sojae races 4, 7, or 31, seed treated with oxathiapiprolin had significantly higher visual root growth scores compared to non-treated seed. Across 115 field locations from 2018 to 2020, UAV remote sensing image analysis at the V2 growth stage indicated oxathiapiprolin in combination with other fungicides had significantly better emergence, more vigor, and more intense greenness compared to non-treated controls. Entries treated with oxathiapiprolin in combination with other fungicides had an average +161 kg ha–1 yield difference compared to non-treated entries from 2018 to 2020. Oxathiapiprolin as a seed treatment is an effective management tool for soybean producers, providing efficacy against P. sojae, and improving emergence, vigor, greenness, and final yield.