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Title: Identifying economic hurdles to early adoption of preventative practices: The case of trunk diseases in California winegrape vineyards

Author
item KAPLAN, JONATHAN - California State University
item TRAVADON, RENAUD - University Of California
item COOPER, MARIA - University Of California - Cooperative Extension Service
item HILLIS, VICKEN - University Of California
item LUBELL, MARK - University Of California
item Baumgartner, Kendra

Submitted to: Wine Economics and Policy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/18/2016
Publication Date: 11/25/2016
Citation: Kaplan, J., Travadon, R., Cooper, M., Hillis, V., Lubell, M., Baumgartner, K. 2016. Identifying economic hurdles to early adoption of preventative practices: The case of trunk diseases in California winegrape vineyards. Wine Economics and Policy. 5(2):127-141. doi: 10.1016/j.wep.2016.11.001.

Interpretive Summary: Trunk diseases pose a serious threat to winegrape production. Despite the fact that every vineyard in California eventually develops one or more trunk diseases, and that not managing trunk diseases leads to significant yield losses, many grape growers routinely wait to adopt field-tested, preventative practices (delayed pruning, double pruning, application of pruning-wound protectants) until after vines start to show symptoms of trunk diseases (i.e., vines are cleary infected). We evaluate the monetary gains from adoption of preventative practices before symptoms appear in young, healthy vineyards (3 and 5 years-old) versus in mature, diseased vineyards (10-years-old). Our economic analysis suggests that growers do indeed benefit from adopting preventative practices and gain the most when they adopt these practices in 3-year-old vineyards, which can increase the vineyard’s profitable lifespan by more than 50%. However, because trunk disease symptoms do not appear until years 8-10, it may take longer (2-10 years) for practices adopted in year 3 to outperform no action, whereas it may take only 0-4 years when adopted in year 10. This longer time lag required to see the effects of preventative practices in young vineyards may contribute to a negative perception of practice efficacy. Given our findings of the economic losses of delayed adoption, coupled with the widespread nature of trunk diseases in California, extension tools should communicate the economic benefits of early adoption.

Technical Abstract: Trunk diseases pose a serious threat to winegrape production. Despite the high likelihood of infection and the substantial yield losses from not managing trunk diseases, many practitioners routinely wait to adopt field-tested, preventative practices (delayed pruning, double pruning, application of pruning-wound protectants) until after disease symptoms appear in the vineyard. We evaluate the gains from adoption of preventative practices before symptoms appear in young, healthy vineyards (3 and 5 years-old) versus mature, diseased vineyards (10-years-old) by simulating winegrape production in five different regions of California. We find growers benefit from adopting preventative practices and gain the most when they adopt these practices in 3-year-old vineyards, which can increase the vineyard’s profitable lifespan by more than 50%. However, because symptomatic vines are typically not present until around year 10, it takes 2-10 years for practices adopted in year 3 to outperform no action and 0-8 years when adopted in year 5, but only 0-4 years when adopted in year 10. This longer time lag required to observe the economic benefits of preventative practices in the field, even when timed properly (i.e., starting in young vineyards, before symptoms appear), may contribute to a negative perception of practice efficacy. Further, under a scenario in which preventative practices are both expensive (>$200/acre) and ineffective (25% disease control efficacy), only growers with perceived probabilities of infection greater than 0.5 are likely to adopt early. Given our findings of the economic consequences of delayed adoption, coupled with the widespread nature of trunk diseases in California, extension tools should communicate the economic benefits of early adoption.