Remove nearby weeds and any volunteer plants from previous seasons. Destroy all plant debris from the garden after harvest that may have been diseased. Not handling plants when they are wet will reduce the spread of disease-causing organisms. The fungus, Phoma lingam , causes blackleg. The symptoms of black leg are ash gray spots speckled with tiny black dots on the leaves and stem.
Stems become girdled, and the plants wilt and die.
Moist conditions favor development of this disease. The fungus, Rhizoctonia solani , causes wirestem. Stems of plants become constricted and brittle at the soil line. The plant becomes stunted and may rot at the soil line. This disease is more severe on fall cole crops when the soil is warm.