Presently, Vitis vinifera grape production in Alabama and the southeastern U.S. is extremely limited due to Pierce’s disease (PD), caused by the bacterium Xylella fastidiosa (Xf) and vectored by insects from the family Cicadellidae. In 2019, UC Davis grape breeding program has released five PD resistant predominantly V. vinifera cultivars which can help sustain the vinifera grape cultivation in the region. Although these new cultivars are currently available, no V. vinifera grape production and management recommendations exist for Alabama conditions. An experimental vineyard was planted at the Chilton Research Extension Center, AL in 2017 to determine the effect of planting distance on vegetative growth and productivity of PD resistant, predominantly V. vinifera advanced selection ‘502-20’. The experiment utilizes a randomized complete block design consisting of three blocks with three vines per block. Vines were planted at an in-row distances of 1.8m, 2.1m and 2.4m and a between row distance of 3.7m and trained to a Watson system. Vine phenology, vegetative growth, yield, and fruit quality characteristics data were recorded during the period of vine establishment (2019-2023). Our results suggest there was a significant treatment by year interaction effect on pruning weight with the lowest pruning weight of 0.8 kg/vine found for vines at an in-row spacing of 2.1m during 2021. Treatment by year interaction also resulted in the highest yield per vine (28.0 kg/vine) measured for vines planted at 2.4m in 2021. Planting distance of 2.4m resulted in a significant increase of the number of clusters per vine during 2021 and 2022 seasons, while no vine spacing effect was found to account for differences in cluster weight, berry mass, or total soluble solids (TSS). Current results indicate planting distance of 2.4m x 3.7m can increase the yield of ‘502-20’ during the years of vine establishment and contribute to sustainable production of PD resistant predominantly V. vinifera grapes in Alabama conditions. Further research will be conducted to expand current knowledge and assist in the development of management recommendations for the successful production of V. vinifera grapes in the region.
