White mold development is favored by cool, cloudy, wet, humid weather at flowering. The disease is more problematic in soybeans in high-yield environments where high plant populations, narrow row spacing, and an early-closing canopy are commonly used.
By X.B. Yang, Department of Plant Pathology
The 2009 growing season had record cool weather in July that was ideal for soybean white mold occurrence. The disease was widespread in the north central region of the U.S. and agronomists even in southern Iowa observed this disease in many soybean fields. In northern Iowa, patches of soybean killed by this disease were obvious in many soybean fields along the highways. Some farmers reported losses totaling more than $10,000 from this disease.
