This practice reduces inoculum of the fungus, thus limiting disease. Keep the fruit planting and surrounding areas free of weeds and tall grass. This practice will promote rapid drying of vines, and thereby limit infection by the fungus. Where feasible, cultivate the vineyard before bud-break to bury the mummified berries. Diseased berries covered with soil do not produce spores that will reach the developing vines.
Grape cultivars differ in their susceptibility to black rot.
The reactions of many grape cultivars to black rot and four other important diseases are given in the Table below. Cultivars with large, juicy berries are the most susceptible ones. In general, grapes that ripen late in the season are affected the least. All commercial cultivars now grown in Illinois are sufficiently resistant if adequately protected during prolonged rainy periods with a fungicide spray program. Use protective fungicide sprays, which are needed in wet seasons, to protect the developing new growth.