Disease Susceptibility of Interspecific Cold-hardy Grape Cultivars in Northeastern U.S.A.

Susceptibility to economically-important diseases of grapes is critical to the evaluation of germplasm recommended for commercial production and for development of sustainable production systems. In 2018-2019, nine cold-hardy grape cultivars including ‘Brianna’, ‘Crimson Pearl’, ‘Itasca’, ‘Louise Swenson’, ‘Marechal Foch’, ‘Marquette’ ‘Petite Pearl’, ‘St. Pepin’, and ‘Verona’ were evaluated on non-treated vines for susceptibility to downy mildew, powdery mildew, black rot, anthracnose, Phomopsis leaf spot and fruit rot, and Botrytis bunch rot. No cultivars were consistently disease-free, and all exhibited some degree of black rot and powdery mildew infection. Relative susceptibility to disease was not consistent across both years, but ‘Brianna’ had greater incidence of black rot and ‘Louise Swenson’ showed lower incidence of powdery mildew in both years. The relatively new cultivars ‘Crimson Pearl’ and ‘Verona’ exhibited comparatively moderate disease susceptibility overall. Growers typically manage diseases with fungicides on commercial farms, so cultivar susceptibility is just one component of a sustainable pest management and production system.