Elina Coneva,* Andrej Svyantek, Andy Walker, and Edgar Vinson
*Auburn University, 101 Funchess Hall, Auburn, AL 36849 (edc0001@auburn.edu)

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 PD-resistant V. vinifera selections developed at UC Davis, 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 an environment with high PD pressure. The experimental vineyard is a RCBD with six blocks and five vines/block. No PD infection was detected during plant establishment. Studies on vine phenology, vegetative development, and cropping potential were initiated in 2015. Selections 502-10 and 502-01 started their development two to four days prior to 501-12. All selections initiated budbreak at the end of March. Vines had fully-developed canopies by April 20. Selection 502-01 had the earliest flowering season; however, all selections reached full flowering by May 5. All selections grew vigorously during the years of vineyard establishment. Fruit of selection 502-10 matured early in the season and was harvested in mid-August, followed by 502-01 at the end of September to early October. The selection 501-12 ripened late and was ready to harvest in the second half of October. The selections differed in yield per vine, but all were highly productive. Cumulative yield per vine for 2012 to 2015 was greatest (28 kg/vine) for the late-season 501-12, while the early- and mid-season selections produced 25.2 and 23.8 kg/vine, respectively. Early-season selection 502-10 had the largest cluster size among the group: 467 g on average in 2015. Based on six years of observations, the study results are encouraging. The newly introduced PD-resistant grape selections have the potential to improve grape production sustainability in the southeastern region and enhance the agriculture and food systems.

Funding Support: Auburn University, AL