Downy mildew is a major disease of grapes throughout
the eastern United States. The fungus causes direct
yield losses by rotting inflorescences, berries, clusters and
shoots. Indirect losses can result from premature defoliation
of vines due to foliar infections. This premature
defoliation is a serious problem because it predisposes the
vine to winter injury. It may take a vineyard several years
to fully recover after severe winter injury.