White mold photos taken by Golden Harvest Agronomy Manager Steve WilkensWhite mold, or Sclerotinia stem rot, is a widespread soybean fungal disease. Losses can be extreme depending on the year and amount of soil inoculum. Though white mold symptoms aren’t prevalent until late in the season, watch environmental triggers to help prevent further disease because white mold can significantly decrease yield and spread to more fields if not managed properly.
Disease developmentWhite mold infections occur at flowering in sustained, wet soil or high humidity. According to the
Crop Protection Network, white mold thrives in temperatures lower than 85° F.
Unless you’re scouting for white mold, foliar symptoms of yellow and/or brown leaves won’t appear until the fungus has progressed enough to kill the plant. The
University of Wisconsin-Extension encourages examining stems for white mold fungus, which begins as gray to white lesions at the nodes. The disease starts as fluffy or cottony white stem growth, and eventually turns dark black along the stem or pods. As soybeans become dry or die, the stems will appear bleached, or light in color.
Prevention and managementGet ahead of white mold by scouting fields early and checking them throughout the season. If your fields have a history of white mold or you experience cool, wet and humid weather at flowering, consider an R1 fungicide application to most effectively reduce disease.
If white mold affects your soybeans each year, examine your management practices. Help reduce the future fungal levels by considering plant populations, row spacing, crop rotation and deep tillage to bury the residue.
Soybean variety selection is also critical. Golden Harvest has excellent disease-tolerant, high-yielding varieties, including industry-leading white mold tolerant options. Check out the Golden Harvest
soybean product finder to see how varieties stack up against white mold. Contact your
Golden Harvest Seed Advisor with questions or for more insights on managing white mold.
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