RT Journal Article SR Electronic T1 Delaying Budbreak to Reduce Freeze Damage: Seasonal Vine Performance and Wine Composition in Two Vitis vinifera Cultivars JF American Journal of Enology and Viticulture JO Am J Enol Vitic. FD American Society for Enology and Viticulture SP ajev.2021.20076 DO 10.5344/ajev.2021.20076 A1 Meredith J. Persico A1 Donald E. Smith A1 Michela Centinari YR 2021 UL http://www.ajevonline.org/content/early/2021/06/10/ajev.2021.20076.abstract AB Spring freeze events pose a threat to vineyard productivity worldwide. We compared two methods to delay grapevine budbreak for freeze avoidance and evaluated their effects on phenology, yield components, fruit composition, and postharvest parameters, including wine chemistry, carbohydrate storage, and bud freeze tolerance. The two methods to delay budbreak were: a vegetable oil-based adjuvant (Amigo®) applied to dormant buds at 8% and 10% (v/v) and late pruning applied when apical buds reached approximately Eichhorn-Lorenz stage 7. Treatments were applied in 2018 and 2019 on two Vitis vinifera cultivars, Lemberger and Riesling, and compared to a control treatment (no delayed budbreak strategy applied). Amigo and late pruning delayed budbreak compared to control vines for both years and cultivars. The delay in budbreak varied from three to six days for Amigo 8%, five to eight days for Amigo 10%, and 10 to 11 days later for late pruning. In 2019, there was a freezing event near budbreak; compared to control vines, late-pruned Lemberger vines had lower shoot damage when measured during the growing season and higher yield at harvest. Delayed budbreak treatments did not influence wine chemistry either year or consistently affect carbohydrate storage or bud freeze tolerance the following dormant season. However, in Riesling, late pruning reduced cluster and berry weight by up to 34% and 22%, respectively, compared to control vines. Furthermore, our results indicated Amigo 10% may decrease bud survival when applied to Riesling vines. In general, late pruning more effectively delayed budbreak and mitigated freeze damage than Amigo application without negatively affecting vine health and wine composition; however, the cultivar-dependent effect of late pruning on cluster weight is a consideration prior to adoption.