Growing Pierce's disease resistant 87.5% V-vinifera grapes in Alabama
Pierce's disease (PD) has prevented the production of high quality Vitis vinifera grapevines in the southern United States. Recently, the U.C. Davis grape breeding program utilized conventional breeding methods to introgress PD resistance from native American species into elite V vinifera wine and table grapes. In 2010, three of the PD resistant 87.5% V vinifera selections, namely '502-10, '502-01, and '501-12, were planted at the Chilton Research and Extension Center (CREC) near Clanton, Alabama. The experimental vineyard utilizes a RCBD with 6 blocks and 5 vines per block, and is trained to a vertical shoot positioning trellis. Fruit was dropped in 2011 and the first commercial crop was produced in 2012. Our preliminary results suggest during the 2012-2013 seasons selection '502-10' had the lowest pruning weight, while '501-12' had the highest, suggesting '501-12' was the most vigorously growing grapevine in our test. Selection '502-10' started to mature early in the season, followed by the mid-season '502-01, and '501-12' ripened late. The three selections differ in their total yield. The late maturing '501-12' produced the highest crop in both seasons. Selections differed in other crop load characteristics as '501-12' produced the highest number of clusters per vine, while '502-10' had the lowest. Mid-season selection '502-01' produced the largest berries, while the late season selection '501-12' had the sweetest berries in both seasons. Preliminary results on the performance of the newly developed PD resistant V vinifera selections in Alabama are very encouraging. Knowledge gained through this project will aid in development of best management practices and production system recommendations, vital for the establishment of a sustainable grape industry in Alabama and the Southeast.