Renaud Travadon, Department of Plant Pathology, University of California, Davis 95616;
Philippe E. Rolshausen, Department of Botany and Plant Sciences, University of California, Riverside 92521;
Walter D. Gubler, Department of Plant Pathology, University of California, Davis;
Lance Cadle-Davidson, United States Department of Agriculture–Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; and
Kendra Baumgartner, USDA-ARS, Crops Pathology and Genetics Research Unit, Davis, CA 95616
Cultivars of European grapevine, Vitis vinifera, show varying levels of susceptibility to Eutypa dieback and Esca, in terms of foliar symptoms. However, little is known regarding cultivar susceptibility of their woody tissues to canker formation. Accordingly, we evaluated the relative susceptibility of V. vinifera cultivars (‘Cabernet Franc’, ‘Cabernet Sauvignon’, ‘Chardonnay’, ‘Merlot’, ‘Riesling’, ‘Petite Syrah’, and ‘Thompson Seedless’) and species or interspecific hybrids of North American Vitis (Vitis hybrid ‘Concord’, V. arizonica ‘b42-26’, V. rupestris × V. cinerea ‘Ill547-1’, and Fennell 6 [V. aestivalis] × Malaga [V. vinifera] ‘DVIT0166’) to canker formation by seven trunk pathogens (Neofusicoccum parvum, Lasiodiplodia theobromae, Phaeomoniella chlamydospora, Togninia minima, Phomopsis viticola, Eutypa lata, and an undescribed Eutypa sp.). Susceptibility was based on the length of wood discoloration (LWD) in the woody stems of rooted plants in duplicate greenhouse experiments. Cultivars of V. vinifera and Concord did not vary significantly in susceptibility to N. parvum or L. theobromae (LWD of 21 to 88 mm at 14 weeks post inoculation; P > 0.16), suggesting that they are similarly susceptible to Botryosphaeria dieback. The table-grape Thompson Seedless was most susceptible to P. viticola (mean LWD of 61 mm at 11 months post inoculation; P < 0.0001). V. vinifera cultivars and Concord showed similar susceptibility to the Esca pathogens, Phaeomoniella chlamydospora and T. minima. Susceptibility to E. lata was greatest in V. arizonica b42-26 (mean LWD of 96 mm at 11 months post inoculation; P < 0.03). In fact, all four American Vitis spp. were more susceptible to Eutypa dieback than the V. vinifera cultivars. Our findings suggest that no one cultivar is likely to provide resistance to the range of trunk pathogens but that certain cultivars may be promising candidates for commercially relevant host resistance in grape-production systems where the dominant cultivars are very susceptible.