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Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Proceedings Publication Acceptance Date: 11/1/2005 Publication Date: 12/5/2005 Citation: Baumgartner, K. 2005. Significance of riparian plants as reservoirs of xyllela fastidiosa for infection of grapevines by the blue-green sharpshooter, graphocephala atropunctata. CDFA Pierce's Disease Control Program Research Symposium. Interpretive Summary: On California’s North Coast, certain plants in wildlands next to vineyards, namely those that occupy riverbanks (riparian hosts), can become infected by the Pierce’s disease pathogen, Xylella fastidiosa (Xf). The importance of a riparian host as a source of the pathogen is related to its ability to support the pathogen and its attractiveness to an insect that spreads Xf to grapevines on the North Coast, Graphocephala atropunctata (blue-green sharpshooter [BGSS]). We quantified BGSSs on five species (California blackberry, California grapevine, elderberry, Himalayan blackberry, periwinkle) of naturally-established plants adjacent to vineyards. We assessed the ability of the same species to support Xf, using controlled inoculations of potted plants kept in screenhouses in the field. No species were characterized by both an abundance of BGSSs and a high frequency of Xf detection. A 71% frequency of Xf detection in periwinkle suggests that, regardless of having the fewest BGSSs (0.4 nymphs and 0.9 adults per sample), infrequent visitations may result in a high acquisition rate. California grapevine supported eight times as many nymphs and three times as many adults as periwinkle, suggesting that frequent visitations may offset its significantly lower infection rate (19%). California blackberry, elderberry, and Himalayan blackberry are likely less important pathogen reservoir because Xf was infrequently detected in their tissues and they hosted few BGSSs. Technical Abstract: On California’s North Coast, plant species in natural habitats adjacent to vineyards, namely riparian areas, are non-crop hosts of Xylella fastidiosa (Xf). The importance of a riparian host as a pathogen reservoir is related to its ability to support pathogen populations and its attractiveness to the vector, Graphocephala atropunctata (blue-green sharpshooter [BGSS]). We quantified BGSSs on five species (California blackberry, California grapevine, elderberry, Himalayan blackberry, periwinkle) of naturally-established plants adjacent to vineyards. We assessed the ability of the same species to support Xf, using controlled inoculations of potted plants kept in screenhouses in the field. No species were characterized by both an abundance of BGSSs and a high frequency of Xf detection. A 71% frequency of Xf detection in periwinkle suggests that, regardless of having the fewest BGSSs (0.4 nymphs and 0.9 adults per sample), infrequent visitations may result in a high acquisition rate. California grapevine supported eight times as many nymphs and three times as many adults as periwinkle, suggesting that frequent visitations may offset its significantly lower infection rate (19%). California blackberry, elderberry, and Himalayan blackberry are likely less important pathogen reservoir because Xf was infrequently detected in their tissues and they hosted few BGSSs. |
