Small purple spots develop on dying leaves. These lesions resemble those caused by Alternaria macrospora . Symptoms usually appear first on oldest leaves at bloom. Areas of leaf margin wilt then turn yellow. The entire leaf eventually may wilt and turn yellow.
Leaves defoliate prematurely.
In cross-section, a brown layer of tissue appears just below the bark of the lower stem. Bolls may open prematurely. These symptoms are difficult to distinguish from Verticillium wilt. Most varieties are somewhat resistant. Maintain soil pH at 6.0-6.5, and use recommended rates of fertilizers.