Determining the threat of Pierce's disease to Virginia vineyards

Pierce's disease (PD) is a vascular disease of grapevines caused by Xylella fastidiosa (Wells et al.) (Xf) which is transmitted by xylophagous insect vectors. PD infection in Virginia vineyards was thought to be isolated to southeastern portions of the state as there have been no reports of vine loss in western Virginia and cold winter temperatures experienced there limit the effects of the bacterium from year to year. Upward trends in winter temperatures have raised PD concern in the mid-Atlantic. My risk assessment study found PD symptomatic vines beyond the modeled boundary for infection, confirmed Xf-positive with DAS-ELISA. Yellow sticky traps were used to survey Virginia vineyards throughout the 2006 and 2007 growing seasons to identify sharpshooter (Cicadellinae) species in six growing regions. Graphocephala versuta (Say) and Oncometopia orbona (Fabricius) (Hemiptera: Cicadellidae) were trapped in the greatest abundance and were both present in every region surveyed. This study uses geographical representation of climatological data to estimate risk for Pierce's disease.