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United States Department of Agriculture

Agricultural Research Service

Title: Persistence of Xylella Fastidiosa in Riparian Hosts Near Northern California Vineyards.

Authors
item Baumgartner, Kendra
item Warren, Jeremy - USDA, ARS, CPGRU

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 7, 2005
Publication Date: October 1, 2005
Citation: Baumgartner, K., Warren, J.G. 2005. Persistance of xylella fastidiosa in riparian hosts near northern california vineyards.. Plant Disease. 10: 1097-1102.

Interpretive Summary: The spread of Pierce’s disease (PD) from riparian hosts to grapevines on California’s North Coast is likely affected by populations of the pathogen, Xylella fastidiosa, in riparian hosts, given that the proportion of insect vectors, Graphocephala atropunctata (blue-green sharpshooters, BGSSs), that acquire the pathogen when feeding is known to be related to pathogen populations in plant tissue. Riparian hosts that do not maintain sufficient pathogen populations for BGSS acquisition may not be significant inoculum reservoirs. We examined pathogen populations in systemic riparian hosts (California blackberry, California grapevine, elderberry, Himalayan blackberry, periwinkle) at two coastal locations (Mendocino, Napa), with two quantitation methods (culturing, real-time PCR), from 2003 to 2004. In summer and autumn, periwinkle had significantly higher pathogen populations than Himalayan blackberry and California grapevine at both locations. Nonetheless, all three species had pathogen populations above the threshold for BGSS acquisition in summer and autumn, at both locations. Our results suggest that the presence of periwinkle, Himalayan blackberry, and California grapevine in riparian areas adjacent to vineyards may increase the risk of Pierce’s disease.

Technical Abstract: The spread of Pierce’s disease (PD) from riparian hosts to grapevines on California’s North Coast is likely affected by Xylella fastidiosa (Xf) populations in riparian hosts, as the proportion of Graphocephala atropunctata (blue-green sharpshooters, BGSSs) that acquire Xf is a function of Xf populations in plant tissue. Riparian hosts that do not maintain sufficient Xf populations for acquisition may not be significant inoculum reservoirs. We examined Xf populations in systemic riparian hosts (California blackberry, California grapevine, elderberry, Himalayan blackberry, periwinkle) at two coastal locations (Mendocino, Napa), with two quantitation methods (culturing, real-time PCR), from 2003 to 2004. In summer and autumn, periwinkle had significantly higher Xf populations than Himalayan blackberry and California grapevine at both locations. Nonetheless, all three species had Xf populations above the threshold for BGSS acquisition in summer and autumn, at both locations. The only Xf-positive plants detected in spring at both locations were periwinkle and Himalayan blackberry, suggesting that these invasive weeds may contribute to long-term survival of Xf in areas with low overwinter survival of BGSS. Higher Xf populations in California grapevine, Himalayan blackberry, and periwinkle in Napa, relative to plants in Mendocino, may partially explain the higher PD incidence in Napa vineyards.

Last Modified: 12/20/2014
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