Growth and development of Pierce’s disease-tolerant hybrid bunch grapes in the southeastern USA

In the humid subtropical climate of the southeastern region of the USA, commercial cultivation of European (Vitis vinifera L.) and hybrid bunch grapes has largely been prevented by the presence of Pierce’s disease (PD), a bacterial infection caused by Xylella fastidiosa, a Gram-negative bacterium endemic to the region. Consequently, only PD-resistant or -tolerant grape cultivars can currently be grown sustainably in the region. Yet, limited research has been conducted to evaluate the yield potential, fruit quality characteristics, and vine growth and development of PD-tolerant/-resistant hybrid bunch grape cultivars in the southeast. An experimental vineyard was established at the Sand Mountain Research and Extension Center, Crossville, AL, in 2008 with a main objective to evaluate the vegetative characteristics and cropping potential of ten PD-tolerant hybrid bunch grape cultivars. The experiment was a random complete block design with four replications. Studied PD-tolerant American and French-American hybrid bunch grape cultivars included ‘Black Spanish’, ‘Blanc du Bois’, ‘Champanel’, ‘Conquistador’, ‘Cynthiana’, ‘Favorite’, ‘Lake Emerald’, ‘Seyval Blanc’, ‘Seyval Blanc’ grafted on ‘Couderc 3309’ rootstock (‘Seyval Blanc’/3309C), ‘Stover’, and ‘Villard Blanc’. Based on 2011-2017 results for cumulative yield per vine, the most productive cultivars in our environment were ‘Favorite’ and ‘Villard Blanc’ (yielding 96.3 and 90.0 kg vine(-1) cumulative yield, respectively), while ‘Conquistador’ was the least productive, with 32.4 kg vine(-1) cumulative yield. ‘Blanc du Bois’ also produced high yields during the last three seasons. ‘Villard Blanc’ had the largest fruit clusters throughout the study period, while ‘Champanel’ consistently produced the largest berries, followed by ‘Blanc du Bois’ and ‘Villard Blanc’. Based on their overall performance ‘Villard Blanc’, ‘Black Spanish’, and ‘Favorite’ are considered suitable for sustainable commercial grape production in Alabama and the southeastern USA.