Share Facebook Twitter Google + LinkedIn Pinterest Many times at harvest questions arise about the causes of discolored soybeans. One symptom sometimes observed is a purple staining of seeds (see the picture at top left). This purple staining is caused by a late-season soybean fungal disease that is called Cercospora leaf blight (CLB). When plants are infected by CLB, dark lesions can be observed on leaf surfaces and leaves can exhibit a puckered, leathery appearance. In addition to infection of the leaves, pods can also become infected causing a purple staining of the seed in infected pods.Although CLB is fairly common, it usually develops too late in the season to cause significant damage or yield loss. For more pictures and information on managing Cercospora Leaf Blight, click here.