Delay in the Ripening of Wine Grapes: Effects of Specific Phytotechnical Methods on Harvest Parameters

Due to climate change, the sugar content of grapes in Hungary has increased to such an extent that the high alcohol content alone can make wines disharmonious. In most vintages, this phenomenon is only a problem for early-ripening varieties. In order to prevent and treat this difficulty, we have carried out experiments in grape canopy management for four years with the aim of delaying ripening and thus reducing the sugar content of the grapes. The experiments were set up on an early (Pinot noir) and a late (Welshriesling) variety; two treatments (leaf removal-LR and short topping-ST) were applied and compared to untreated controls in the years 2019-2022. Our results showed that grape juice sugar yield was significantly reduced in all four years and for both cultivars, while the other measured parameters (yield, acidity, pH, and Botrytis infection) were only lightly affected.