Written with contributions by Emmanuel Byamukama, former SDSU Extension Plant Pathologist, and Febina Mathew.
White mold, also known as Sclerotinia stem rot, is a fungal disease of soybean that causes severe yield losses in South Dakota. In 2014, yield loss across the U.S. was estimated at 37.2 million bushels. Portions of fields of irrigated soybeans in South Dakota have shown yield losses of up to 50%. Although white mold can be sporadic in a field, yield losses increase when incidence is higher. For every 10% increase in white mold incidence, there is an estimated reduction in yield of 2-5 bushels per acre. White mold develops often as a few scattered infected plants, but in some years, this disease can reach high levels depending on weather and agronomic practices.