@article {Purcell162, author = {A. H. Purcell}, title = {Spatial Patterns of Pierce{\textquoteright}s Disease in the Napa Valley}, volume = {25}, number = {3}, pages = {162--167}, year = {1974}, doi = {10.5344/ajev.1974.25.3.162}, publisher = {American Journal of Enology and Viticulture}, abstract = {The spatial pattern of Pierce{\textquoteright}s disease of grapevines was studiied by mapping diseased grapevines in eight vineyard plots in the Napa Valley, California. The percentage of diseased vines was highest nearest natural riparian vegetation, declining with distance (up to 400 to 500 ft) from natural source areas of the principal leafhopper vector, Hordnia circellata (Baker). The slope of disease dispersal gradients annual changes in apparent infection rate, and the overall incidence of Pierce{\textquoteright}s disease varied among grape varieties in adjacent plantings with similar exposure to vector source areas.}, issn = {0002-9254}, URL = {https://www.ajevonline.org/content/25/3/162}, eprint = {https://www.ajevonline.org/content/25/3/162.full.pdf}, journal = {American Journal of Enology and Viticulture} }