Avoid wounding plants during cultivation and harvesting. Bury crop residue and rotate with corn or small grain to reduce bacterial populations. Black rot is caused by the bacterium Xanthomonas campestris pv. Black rot symptoms appear initially as V-shaped areas along the outer leaf edges. As the disease progresses leaf veins turn black, plants become stunted, wilt and usually die.
Tolerant varieties are available.
Black leg is caused by the fungus Leptosphaeria maculans. Symptoms first appear as black, round spots on leaves and sterns. As disease progresses, spots enlarge and become gray in the center with small black dots. Severely infected plants are stunted and may have a constricted stem at the soil line. Apply fungicides when needed.