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

A four-year study (1998-2001) compared the long-term performance of bilateral cordon trained, spur pruned Chardonnay and Merlot grapevines trellised to the vertically shoot positioned trellis system (VSP), the vertically divided Smart-Henry trellis system (SH) and the vertically separated Smart-Dyson trellis system (SD). Vine vigor at the site was moderate. Compared to the VSP, the SH and SD systems reduced canopy density and improved fruit zone microclimate. SD and SH vines had fewer leaf layer numbers and greater amounts of sunlight in their fruiting zones compared to VSP vines. Primary, lateral and total leaf areas per vine were similar among the treatments, indicating that differences in canopy density were a result of canopy division or separation along with an increase in total canopy volume available for foliage distribution. Over the course of the study the yield of SH and SD vines was generally10%to 15%greater compared to VSP vines. Pruning weight per vine and the yield:pruning weight ratios were generally similar among the treatments in both cultivars. In the first year of evaluation fruit on downward-oriented shoots on the SH system ripened more slowly compared to shoots oriented upward, but these differences diminished as the yield of the lower fruiting zone in this system declined. No significant difference in fruit ripening was observed due to shoot orientation in the SD. Few differences in combined fruit (upper and lower canopies) soluble solids, titratable acidity and pH were observed among the treatments in either cultivar over the four-year period. Fruit and wine color (Merlot) were improved in the SD and SH treatments, and wines from these treatments in the Merlot were preferred over the VSP system in three of the four years of the experiment. We found that SD and SH trellis systems significantly improved both yield and fruit composition compared to the VSP system. SD is preferred over SH based on ease of establishment and culture, as well as long-term productivity; both vigor and productivity of downward trained shoots in the SH declined over the course of the study.

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