The use of resistant cultivars has reduced losses. Young expanding leaves are extremely susceptible, while fully expanded leaves are more resistant to invasion. However, because visible lesions develop nearly two weeks after invasion, lesions are never seen on young expanding leaves. The foliar lesions measure up to 5mm in diameter but may coalesce to form larger spots. As lesions age, the center becomes tan to nearly white and the margin darkens.
Lesions also occur on stems and pods.
Crop rotation and plowing under crop residues will reduce disease incidence. Fungicides applied at the late flowering and beginning seed growth stages will protect against frogeye infection. Several races of the pathogen have been identified, but cultivars with resistance to all known races are available. Cercospora leaf blight is a late season disease that is often mistaken for early senescence. Symptoms are first observed at the beginning of seed set.