Such infections do not appear to affect Concord crop yield or quality. On V. vinifera and highly susceptible hybrid cultivars, continued suppression of foliar mildew generally is required at least until veraison to avoid early defoliation. Good management of late-season leaf infection also reduces disease pressure the following year, by limiting the number of fungal fruiting structures that overwinter and initiate infection in the spring. Prebloom through fruit set is the most critical period for managing fruit infections on all cultivars, and programs should be especially strenuous if weather is wet during this time. Continued protection through veraison may be beneficial for attaining maximum fruit quality on V. vinifera and susceptible hybrid cultivars, and is generally required to prevent premature defoliation.
Cultural practices can reduce disease severity.
Plant in sites with good air circulation and sun exposure. Use a training system that allows good air movement through the canopy and prevents excess shading.