P-075 - Optimizing the Use of Coniothyrium minitans for Management of Sclerotinia Stem Rot of Soybean (Glycine max)

Sclerotinia stem rot (SSR; white mold) is caused by the soilborne fungus, Sclerotinia sclerotiorum, one of the top ten most devastating diseases of soybean (Glycine max L) in the U.S. While cultural and chemical practices can be effective for managing SSR, they do not provide complete control by themselves. Coniothyrium minitans has emerged as a promising biological control tool, offering sustainable and effective management of SSR. The first objective of this study was to investigate the effective application rate of C. minitans (Commercial product: Contans), applied to different soil types for reduction in disease index and yield preservation in soybean. The second objective was to assess the efficacy of C. minitans in reducing the survival and viability of sclerotia left on the surface or buried in different soil types. Higher application rates of C. minitans may be required for reduction in disease index and higher yield, however no significant differences were noted in the initial rate studies (P>0.05). At 120 days after the application of C. minitans, treatments where sclerotia were buried and C. minitans applied resulted in significantly lower survival (P< 0.01) and viability (P< 0.01) of sclerotia in high organic matter soil. In contrast, no statistically significant differences were observed between individual or combined treatments of C. minitans in sandy soils (P>0.05) during the same timeframe. Studies are ongoing and results will be used to refine integrated management strategies that include the use of C. minitans to improve SSR management in soybean.