Cercospora leaf spot of Soybeans

Cercospora kikuchii infects leaves, stems, and pods of soybean, where it causes purple seed stain and Cercospora leaf blight. Purple seed stain is conspicuous and easily identified. It is characterized by irregular blotches varying from light to dark purple and ranging from a tiny spot to the entire area of the seed coat. Purple seed stain does not reduce yields directly, but it may cause reduced stands. Under field conditions, symptoms of Cercospora leaf blight are observed at the beginning of and throughout seed set. Reddish purple, angular-to-irregular lesions occur on upper leaves exposed to sunlight. Numerous infections cause rapid chlorosis and necrosis of leaf tissue, resulting in defoliation. Cercospora leaf blight is an economically important disease and can cause substantial yield loss.