Purple Seed Stain and Cercospora Leaf Blight

Abstract

The fungus Cercospori kikuchii Gardner causes purple seed stain of soybeans and Cercospora leaf blight of the soybean plant. Most research pertaining to this fungus has focused on the purple staining of seed. In the United States, purple seed stain was first observed in 1924 in Indiana. Purple seed stain does not reduce yields, but may cause reduced stands. Cercospora leaf blight is an important economic disease of soybean plants in the southern United States. Cercospora kikuchii overseasons in infected leaf lamina, petioles, stems and seed of soybean plants. The effect of temperature and moisture on infection by C. kikucbii was evaluated with Forrest soybeans. Cultivars differ greatly in their susceptibility to purple seed stain and Cercospora leaf blight. Most appear to have some degree of resistance, and usually do not have a high percentage of purple-stained seed. Athow reported that PI 80837 possesses a high degree of resistance to seed stain.