Effects of Differential Pruning on Cabernet Sauvignon Grapevines

Abstract

Cabernet Sauvignon vines in one Napa Valley and two Davis, California vineyards were differentially pruned to investigate the problem of bud failure or weak shoots on basal and mid-cane segments. Treatments were: (T1) nine 4-node spurs, (T2) four 8-node canes, (T3) two 15-node canes, (T4) four 17-node canes with 50% fruit thinned at véraison, and (T5) two arched canes draped over the foliage wire. Data from a separate plot of cordon-trained vines with twenty 2-node spurs were included for comparison. Bud failure was reduced for treatments with shorter bearing units and for arched canes. Distribution of fruit and vigor of mid-cane shoots were improved by arching canes. Although over half the clusters on cordon-trained vines came from noncount buds (spur base buds and latent buds), these clusters were considerably smaller than clusters on shoots from spurs. The major contribution of crop, therefore, was from count buds. Differences due to vineyard site outweighed any differences due to pruning. Primary and second crop and fruit composition were affected by pruning method. Arching canes is a worthwhile practice when cane pruning Cabernet Sauvignon vines. Training Cabernet Sauvignon to cordons appears to be a most effective system.