White oaks are the most susceptible of many oak species to this leaf blotching disease. Twig infections occur but are not significant except as sources of overwintering fungal inoculum from year to year. Leaves and shoots are infected during cool, wet spring conditions causing leaf blotches that often are strictly delimited by leaf veins. Eventually, lesions become a papery tan color and some leaf shriveling occurs. Multiple cycles of infection can occur. Just as leaves near maturity, lesion size lessens, and once leaves mature they become fully resistant by early to mid summer. Spray treatments are not particularly effective.