2018 ASHS Annual Conference

Pierce’s Disease (PD), caused by the bacterium Xylella fastidiosa, is the major limiting factor for production of Vitis vinifera grapes in the southeastern United States. Three ‘Dog Ridge’ grafted PD resistant V. vinifera selections developed at the UC Davis, namely ‘501-12’, ‘502-01’, and ‘502-10’ were planted at the Chilton Research and Extension Center, Clanton, in 2010 to study their resistance to PD and overall performance in high PD pressure environment. The experimental vineyard is a RCBD with 6 replications and 5 vines/replication. Studies on vines’ phenology, vegetative development, cropping potential, and fruit quality were conducted during 2012-2017 seasons. All selections initiated bud break stage at the end of March and had fully developed canopies by late April. Selection ‘502-01’ had the earliest flowering season. Our results suggest all selections grew vigorously through the years of vineyard establishment. Results for dormant pruning weights revealed high vigor for all selections. Fruit of selection ‘502-10’ matures early in the season, and is harvested in mid- August, followed by ‘502-01’ harvested end of September to early-October. ‘501-12’ ripens late and is usually harvested in the second half of October. Studied selections differed in total yield per vine, but were highly productive. Cumulative yield per vine for the period 2012-2017 was the highest for the late season ‘501-12’. Early-season selection ‘502-10’ had the largest cluster size among the group with an average cluster weight of 467 g on average in 2015. Based on six years of observations, the study results are encouraging. No PD infection was detected during the period of plant establishment. The newly introduced PD resistant grape selections have the potential to improve the grape production sustainability in the southeastern region and enhance the agriculture and food systems.