Delaying winter pruning, after pre-pruning, alters budburst, leaf area, photosynthesis, yield and berry composition in Sangiovese (Vitis vinifera L.)

Background and Aims Earlier ripening of grapes due to global warming could be mitigated by delaying hand pruning on pre‐pruned canes. Hand pruning on pre‐pruned vines was delayed until after distal buds on canes had burst for Sangiovese (Vitis vinifera L.) vines, and the effect on phenology, canopy development, leaf gas exchange, yield and berry development and composition was assessed. Methods and Results Pre‐pruned vines, which were subsequently hand‐pruned during winter, were compared to vines where hand pruning was delayed (DP) until shoots from distal nodes of canes had burst and developed 3–4 (DP3) or 7–8 (DP7) expanded leaves. Delayed pruning delayed budburst by about 30 days in DP3 vines and 37–47 days in DP7 vines, which led to a slowing of canopy development and berry growth. Veraison was delayed by between 10 and 20 days. Yield was substantially reduced by delaying hand pruning but the concentration of phenolic substances and the acidity of berries was increased. Conclusions Delaying hand pruning on vines that had already been pre‐pruned delayed budburst, anthesis and veraison, reduced yield and significantly affected berry composition. The magnitude of these effects increased with the length of the pruning delay. Significance of the Study Delaying hand pruning on pre‐pruned grapevines may represent a promising technique to mitigate against some of the deleterious effects of global warming in vineyards.