Oral Technical Session: Disease Control and Pest Management

100-O

Grower perceptions of preventative practices for management of trunk diseases of grape.
K. BAUMGARTNER (1), R. Travadon (2), V. Hillis (2), J. Kaplan (3), M. Cooper (2), M. Lubell (2)
(1) USDA ARS, Davis, CA, U.S.A.; (2) UC Davis, Davis, CA, U.S.A.; (3) California State University, Sacramento, Sacramento, CA, U.S.A.

Trials on prevention of trunk diseases (e.g., Eutypa dieback) show that three practices [delayed pruning, double pruning, pruning-wound protectants] prevent pruning-wound infections by 25-100%. Nonetheless, they are often not adopted until disease incidence is >20% in mature vineyards. There are no eradicative controls. Our goal is thus to encourage adoption in young vineyards. We surveyed 350 grape growers in five California regions (Napa-Sonoma, Central Coast, N. San Joaquin, S. San Joaquin, N. California) using the audience-response software Turning Point, in extension meetings. Growers answered questions on practice usage (never to always), vineyard age when practice was adopted (0-3, 4-7, 8-12, and 13+ years), and perceptions of disease-control efficacy and cost-effectiveness (ineffective to effective). In all but one region (Napa-Sonoma), preventative practices were adopted in vineyards >8 years old, with mean disease incidence of 15%. Delayed pruning was most common except in Sonoma, where pruning-wound protectants were most common. Growers who adopt a practice in vineyards <8 years old also had positive perceptions of efficacy and cost-effectiveness, suggesting that timing the practice before symptoms appear does indeed maintain yields and is cost-effective. With a clear understanding of their usage and perceptions, we will develop new extension tools that better communicate to growers the case for preventing trunk diseases in young vineyards.