Lesions on the stem at or near the soil line develop rapidly, girdling the stem and result in a sudden and permanent wilt of the plant. The fungus grows downward in the stem and root, rotting the cortical tissue. White mats of mycelium develop on the stem and in adjacent soil. The abundant sclerotia are a good diagnostic feature of this disease. The fungus attacks a wide range of plants and survives for long periods in the soil as sclerotia.
Southern blight is usually a minor disease of beans in California.
Rotation to nonhosts such as corn or small grains for at least 2 years reduces inoculum. Burying plant refuse helps destroy sclerotia. The Regents of the University of California. All rights reserved. For noncommercial purposes only, any Web site may link directly to this page or photo file.