Alternative Trellising Systems for Chardonnay and Merlot Vineyards in the Central Coast

The purpose of this study is to compare the performance of bilateral cordon trained, spur pruned Chardonnay and Merlot grapevines trellised to the vertically shoot positioned trellis system (VSP), the Smart-Henry trellis system (SH) and the Smart-Dyson trellis system (SD) in the Salinas Valley of California. Primary leaf size, as well as primary, lateral and total leaf area per vine, did not differ significantly among the treatments. VSP vines had greater leaf layer numbers in the fruiting zone compared to SD and SH vines, and these treatments had greater amounts of sunlight in the fruit zone compared to the VSP treatment. Vine yield components were similar among the treatments in both cultivars. Compared to upward-oriented canopies, trends toward reduced yields for downward-oriented canopies were observed in Chardonnay, while the opposite was true for Merlot. Pruning weights and pruning weight ratios were similar among the treatments in both cultivars. Fruit on downward-oriented shoots on the SH and SD systems generally ripened more slowly compared to shoots oriented upward. At harvest, however, no significant differences in combined fruit (upper and lower canopies) soluble solids, titratable acidity and pH were observed among the treatments in either cultivar. Wine lots made from each treatment will be evaluated in 2000.