TRAP CROPS FOR REDUCING SPREAD OF PIERCES DISEASE

• Author(s): Weber, Ed; Purcell, Alexander; Walker, Andrew;
• Abstract: Where the blue-green sharpshooter (BGSS), Graphocephala atropunctata, is the primary vector of Xylella fastidiosa (Xf), Pierces disease (PD) generally occurs near the edges of vineyards. The distribution of diseased vines matches the springtime movement of sharpshooters from overwintering habitats into vineyards (Varela, Smith and Philips 2001). Attempts to manage PD often include late winter or early spring insecticide applications to the edge of the overwintering habitat in order to limit the springtime movement of sharpshooters. This practice may reduce PD incidence, but often fails due to limitations in available insecticides, difficulty in timing sprays to coincide with vector movement, differences in PD susceptibility due to variety (Purcell 1979) or vine age, and regulatory issues that prevent treatment of the overwintering habitat. Another possible control strategy is growing a buffer of plants that are not damaged by Xf and treating them with persistent, systemic insecticides to impede the movement of BGSS vectors into the vineyard. We initiated this project in 1999 to examine the effects of an insecticide-treated grapevine trap crop on the incidence of PD. We selected St. George rootstock (Vitis rupestris) for the trap crop because it buds out early in the spring, is attractive to BGSS and is not killed by PD. We planned to treat trap crop vines during fall or winter with soil-applied imidacloprid (Admire, Bayer Corporation). At the time, we believed that adult BGSSs feeding on treated trap crop vines would quickly acquire a lethal dose of imidacloprid.
• Publication Date: Dec 2002
• Journal: 2002 Pierce's Disease Research Symposium