The fungus survives in the soil and on plant debris, as well as on certain weed hosts. Infection usually begins at flowering during prolonged periods of high humidity and warm temperatures. Symptoms include leaf spots, leaf blighting, or defoliation. Tissue in the center of lesions falls out giving the plant a ragged appearance. Brown lesions may also form on the petioles, stems, and pods.
Severe infection causes pod blight.
Some cultivars are more tolerant and should be planted in fields with a history of aerial blight. This destructive disease occurs regularly in areas with high humidity. In other areas, the occurrence of frogeye is sporadic, but is more severe in seasons with frequent rainfall. When a high percentage of leaves are heavily infected, serious yield loss is common. The use of resistant cultivars has reduced losses.