It can cause complete crop loss in warm, humid climates. Because of climatic requirements, this disease is especially important in the viticultural regions of the midwestern and eastern United States. There is wide variation in disease susceptibility among native American cultivars, Vitis vinifera and its hybrids. In general Vinifera hybrids on Long Island are very susceptible to black rot. All green tissues of the vine are susceptible to infection.
Leaves are susceptible for about one week after they unfold.
Petiole infection may cause the leaves to wilt. Shoot infection results in large black elliptical lesions. These lesions may contribute to breakage of shoots by wind. The fruit infection phase may result in substantial economic loss. Berries are susceptible to infection from bloom until they begin to ripen.