Narrow-row soybeans can suppress weeds, but they also can contribute to the development of white mold caused by the fungal pathogen Sclerotinia sclerotiorum. This fungus has become a problem because it can thrive under the closed canopy of narrow-row and drilled soybeans. Severe infestations can reduce soybean yields by 50 to 70 percent, and the pathogen can survive for years in the soil as large, hard masses of fungal tissue called sclerotia.