Pruning after budburst to delay and spread grape maturity

Background and AimsThe shift in phenological development is the most conspicuous biological effect of climate change in vineyards worldwide. Associated with the advancement in maturity there has been a compression of the harvest period that places significant pressure on vineyard and winery infrastructure. Our aims were to test the feasibility of using delayed pruning as a tool to delay ripening and decompress maturity, to establish how much pruning can be delayed before compromising yield, and to compare the response of Cabernet Sauvignon and Shiraz. Methods and ResultsFive pruning dates (from winter up to 3 weeks after budburst) were applied in a commercial vineyard, and we monitored phenology, fruit maturation, and measured yield and its components. The maturation, as determined by sugar concentration, was delayed by up to 3 weeks in Shiraz and by 2 weeks in Cabernet Sauvignon. The yield response varied between pruning dates. The Shiraz vines pruned at the latest phenological stage (E-L 15) recorded a reduction in yield of over 50%; the yield of the other treatments ranged from a 24% reduction to a 55% increase relative to that of the Control. ConclusionMaturity was delayed with mostly neutral or positive effects on fruit composition. Significance of the StudyDelayed pruning offers a real and cost-effective tool to allow the Australian wine industry to adapt to climate change by delaying ripening and decompressing harvest.