Double-Pruning Grapevines as a Management Tool to Delay Berry Ripening and Control Yield

Sangiovese vines mechanically spur-pruned during dormancy in February were 19 subjected to immediate or delayed (post bud-burst) manual finishing to test the potential of a ‘double-pruning’ approach to delay fruit sugar accumulation and limit yield. The treatments were applied in 2014, 2015 and 2016 at BBCH-0 as standard hand finishing on dormant buds (SHF) and as late (LHF) and very late (VLHF) hand finishing at BBCH-14 and BBCH-19, i.e. when the two apical shoots on the mechanically shortened canes were respectively about 10 cm and 20 cm long. While yield per vine was drastically reduced in the VLHF treatment (-43% vs. SHF) due to high incidence of unsprouted (blind) nodes, lower shoot fruitfulness and berries per cluster, yield reduction in LHF was -22% vs. SHF due only to unsprouted nodes incidence. While the fruit ripening profile was not significantly modified in VLHF as compared to SHF, LHF achieved for data pooled over the three seasons a delay in basic fruit composition at harvest as lower total soluble solids and pH and higher acidity which, however, was associated with higher phenolics in comparison to SHF. Overall, LHF proved to be effective at reducing yield per vine to a level that did not require expensive cluster thinning. By reducing berry sugar accumulation, it has the potential to produce wines with lower alcohol and higher phenol content. Noteworthy too is its potential to delay harvest date or increase crop hanging time under specific vineyard conditions.