Survey of North Georgia wine grapes for Pierces disease as related to elevation

• Author(s): Brannen, P.; Chang, Chung-Jan;
• Abstract: Pierces disease (PD), caused by Xylella fastidiosa, has limited wine grape production in the Southeast. Lower temps. negatively impact the bacterium. Increasing elev. results in lower av. temps., and wine grape producers in GA have taken this into account for site selection. A two-year vineyard survey was conducted to determine a relationship between PD and elev. in GA. Samples consisted of new shoots with at least six leaves. When no symptoms were present, 20 random samples were collected. When symptoms were present, 20 symptomatic shoots and 10 asymptomatic shoots were collected for comparison. Elev. was determined through use of GPS units. Samples were processed through ELISA; confirmation was established by plating bacteria on PW media. Epidemic PD levels were observed at 236-242 m (2575% incidence). At 500-542 m elev., PD incidence was low (1%), but PD was consistently observed in both survey years. No PD infections were observed at 542 m elev. The highest elev. sampled was 692 m. Climatic variation may shift the safe zone, but 400 m elev. sites may allow for wine grape production in GA.
• Publication Date: Jun 2002
• Journal: Phytopathology