Disease and cause Symptoms Chemical control Alternative control and remarks Bacterial blight Xanthomonas campestris pv. Small, light green, angular lesions on leaves which turn dark brown. Large numbers of lesions may darken large areas of a leaf. Infected leaves defoliate prematurely. Symptoms rarely occur on bolls or stems in southeast Missouri.
Most varieties have some resistance.
Crop rotation will control this problem. Leaf spots Alternaria macrospora. Small, brown, circular lesions on leaves enlarging to 0.4 inches. Old lesions have gray centers which may fall out. These leaf spot diseases are of minor importance in Missouri and specific controls are not recommended.