Impact of pruning strategy, cluster thinning, and shoot removal on growth, yield, and fruit composition of low-vigor De Chaunac vines

To explore alternative means of crop control on vineyard attributes, 10-yr-old, low-vigor De Chaunac vines were subjected over a 3-yr period to eight crop regulation treatments, which involved combinations of pruning strategy (15 + 10 balanced pruning; 40 nodes per vine), cluster thinning, shoot thinning to one shoot per node, and removal of base shoots. Treatments involving cluster thinning maximized vine size, periderm development, yield components, °Brix, and anthocyanins. Yield per vine was not affected by any treatment. Cane periderm, yield components, and °Brix of cluster thinned, balance pruned vines exceeded those in cluster thinned vines pruned to 40 nodes. Shoot thinning of balance pruned vines did not improve cane periderm formation or yield components over un-thinned vines, but reduced °Brix. Combining cluster and shoot thinning with balanced pruning and base shoot removal proved to be superior to all treatments in every aspect of growth, yield, and fruit composition. Vines pruned to 40 nodes and subjected to base shoot removal and shoot thinning had improved yield components and °Brix over vines shoot thinned only, but were inferior to cluster thinned vines in terms of all vineyard parameters. Crop loads below 7 kg kg −1 cane prunings appear necessary to maintain vine size, yield, and acceptable fruit composition of low-vigor De Chaunac vines.Key words: Vitis, De Chaunac, pruning, cluster thinning, vine