PT - JOURNAL ARTICLE AU - Kendra Baumgartner AU - Renaud Travadon AU - Phillip T. Fujiyoshi AU - Maria Mireles AU - Michelle Moyer TI - Preventing Trunk Diseases with Fungicide Applications to Pruning Wounds in Washington Winegrapes AID - 10.5344/ajev.2022.22019 DP - 2023 Jan 01 TA - American Journal of Enology and Viticulture PG - 0740007 VI - 74 IP - 1 4099 - http://www.ajevonline.org/content/74/1/0740007.short 4100 - http://www.ajevonline.org/content/74/1/0740007.full SO - Am J Enol Vitic.2023 Jan 01; 74 AB - Background and goals Grapevine trunk diseases in the Columbia River Basin of eastern Washington include Cytospora dieback, Eutypa dieback, and Esca. Although some of the causal fungi are known (as Cytospora viticola, Eutypa lata, and Phaeomoniella chlamydospora, respectively), basic epidemiology is not. This makes it difficult to time management practices. The common assumption is that these pathogens infect through pruning wounds during the dormant season, as has been shown for causal fungi of some grapevine trunk diseases in California. As such, we evaluated fungicides for protecting wounds after pruning under eastern Washington conditions.Methods and key findings In March 2019, 2020, and 2021, we evaluated the protection efficacy of pyraclostrobin + fluxapyroxad and thiophanate-methyl sprayed within three days of pruning at an established Vitis vinifera Chardonnay vineyard in Prosser, WA. Within two days of fungicide treatment, C. viticola, E. lata, or P. chlamydospora (2000 spores per wound) were inoculated separately onto spurs, and molecular-detection attempts were made five to eight weeks later (after budbreak). Compared to water-treated spurs, detection rates of C. viticola and P. chlamydospora from thiophanate-methyl-treated spurs were lower in all three study years. Detection rates of E. lata from thiophanate-methyl-treated spurs were lower in one year.Conclusions and significance This suggests that dormant-season spray applications of thiophanate-methyl as a pruning-wound protectant can reduce grapevine spur infection by these pathogens. Little to no rain during the dormant season in eastern Washington may limit opportunities for disease spread, but winter injury to the permanent, woody structure of the vine may create additional infection courts.