This disease is most severe during years with above average rainfall and high relative humidities.
Young leaves are extremely susceptible while older leaves are more resistant.
However, because visible lesions do not develop until 10 to 14 days after infection, young leaves never exhibit symptoms of frogeye leaf spot. On older leaves the lesions measure up to inch in diameter but may coalesce to form larger spots. Young, fully developed lesions have a gray to brown center with a distinct purple to reddish margin. As lesions age, the center becomes nearly white, and the margins darken. Control of frogeye leaf spot is obtained through the use of crop rotation, plowing down old soybean debris, and the use of resistant varieties.