Making the case for early adoption of preventative practices for management of grapevine trunk diseases

Authors: Baumgartner, Kendra; TRAVADON, RENAUD - University Of California; LUBELL, MARK - University Of California; HILLIS, A VICKEN - University Of California; KAPLAN, JONATHAN - California State University; COOPER, M - University Of California - Cooperative Extension Service

Submitted to: American Society of Enology and Viticulture Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2014
Publication Date: 5/15/2014
Publication URL: http://www.asev.org/sites/main/files/file-attachments/2014technicalabstracts.pdf
Citation: Baumgartner, K., Travadon, R., Lubell, M., Hillis, A., Kaplan, J., Cooper, M. 2014. Making the case for early adoption of preventative practices for management of grapevine trunk diseases. American Society of Enology and Viticulture Annual Meeting Abstracts. pp. 80-81.

Interpretive Summary: Researchers have shown that the trunk diseases Botryosphaeria dieback, Esca, and Eutypa dieback can be managed effectively by using delayed pruning, double pruning, and applications of the pruning-wound protectant thiophanate-methyl (Topsin). Despite scientific evidence, these practices are not typically adopted by growers until disease incidence reaches levels of > 20%, which occurs when the vineyard is 8 to 10 years old. Possible explanations include confusing disease management guidelines, discouraging results due to late timing, and negative perceptions of disease control efficacy. There are no efficient eradicative controls. Our goal is thus to encourage early adoption of preventative practices in young vineyards. We surveyed approximately 350 grape growers in five regions of California (Napa-Sonoma, Central Coast, Northern San Joaquin, Southern San Joaquin, and Northern California). Growers answered questions on usage of preventative practices (never to always), vineyard age when practice was adopted (0 to 3, 4 to 7, 8 to 12, 13+ years), and perceptions of disease control efficacy and cost-effectiveness (very ineffective to very effective). In all but one region (Napa-Sonoma), preventative practices were typically adopted in vineyards > 8 years old. Delayed pruning was most common of all three practices, except in Sonoma, where pruning-wound protectants were more common. Growers with positive perceptions of practice efficacy and cost-effectiveness tended to adopt the practice in vineyards < 8 years old, suggesting that timing these preventative practices before trunk disease symptoms become apparent does maintain adequate yields and is thus cost-effective. With a clear understanding of these trends in usage and grower perceptions, we will develop new extension tools that better communicate the advantages of preventing infection in newly-established vineyards.

Technical Abstract: Experimental trials on prevention of trunk diseases Botryosphaeria dieback, Esca, and Eutypa dieback have shown that delayed pruning, double pruning, and applications of the pruning-wound protectant thiophanate-methyl (Topsin) can reduce pruning-wound infections by 25-75%. Despite this biological evidence, these practices are not typically adopted by growers until disease incidence reaches levels of > 20% in mature vineyards. Possible explanations include confusing disease management guidelines, discouraging results due to late timing, and negative perceptions of disease control efficacy. There are no efficient eradicative controls. Our goal is thus to encourage early adoption of preventative practices in newly-established vineyards, before trunk diseases start to impact yields. A survey of approximately 350 grape growers in five regions of California (Napa-Sonoma, Central Coast, Northern San Joaquin, Southern San Joaquin, and Northern California) was conducted in eight meetings organized by extension agents and regional grower groups, using the audience-response software Turning Point. Respondents answered questions on usage of preventative practices (never to always), vineyard age when practice was adopted (0 to 3, 4 to 7, 8 to 12, 13+ years), and perceptions of disease control efficacy and cost-effectiveness (very ineffective to very effective). In all but one region (Napa-Sonoma), preventative practices were typically adopted in vineyards > 8 years old, with 15% of vines showing trunk disease symptoms. Delayed pruning was most common of all three practices, except in Sonoma, where pruning-wound protectants were most common. Growers with positive perceptions of practice efficacy and cost-effectiveness tended to adopt the practice in vineyards < 8 years old, suggesting that timing these preventative practices before trunk disease symptoms become apparent does maintain adequate yields and is thus cost-effective. With a clear understanding of these trends in usage and grower perceptions, we will develop new extension tools that better communicate the advantages of preventing infection in newly-established vineyards.