RESEARCH UPDATE: Pesticide Impact on White Mold (Sclerotinia Stem Rot) and Soybean Yield

By Damon L. Smith, Associate Professor and Extension Field Crops Pathology Specialist, University of Wisconsin-Madison

Hot off the press! New outreach research update – efficacy & economics of products for white mold control in soybean.

  • We performed a meta-analysis on results from multiple research trials conducted in six states over eight years.
  • Some pesticide active ingredients significantly reduce white mold disease severity index (DIX) and preserve yield.
  • Application timing affected disease reduction and yield benefit.
  • Yield loss due to white mold did not occur until 20-25 percent DIX at the R6-R7 growth stage. Considerable yield loss (>10 percent) was observed beginning at approximately 65 percent DIX.
  • Our economic analysis revealed a wide range of probability of return on pesticide investment (ROI).
  • White mold (Sclerotinia stem rot) is caused by the fungalpathogen Sclerotinia sclerotiorum, and the disease frequently ranks among the top yield-reducing soybean diseases in the northern United States. Researchers estimate that white mold caused more than 101 million bushels of soybean yield loss (an estimated value $1.2 billion) in the U.S. and Ontario, Canada (Allen et al., 2017; USDA-NASS, 2017).

The pathogen can survive in the soil as sclerotia for a long time. Furthermore, S. slerotiorum has a broad host range. Both factors present major management challenges. Most commercial soybean cultivars exhibit little host resistance, so in-season management relies heavily on applying fungicides that protect the flowers from infection.

Researchers commonly test chemical products in white mold management trials across the soybean-growing region. For this publication, we used meta-analysis to collate information from these trials into a single database.

To read the rest of this publication, click here.