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Eddy, Marlys E.

Plant and Soil Science

2006

MS

A wine grape industry has recently developed in Vermont. The state currently has approximately 12 ha of grapevines, the majority of which are used for winemaking, and more grapevines continue to be planted. Growers are in need of information about how wine grape cultivars perform under Vermont's cold climatic conditions. An observational study was conducted on the performance of wine grape cultivars that were considered by Vermont growers to have potential for Vermont. The study involved four established commercial vineyards in the Champlain Valley of Vermont. A total of nine wine grape cultivars including Vitis vinifera L. and hybrid species were assessed on the basis of yield and fruit composition parameters in 2004 and 2005. The cultivars 'Arctic Riesling', 'Leon Millot', 'Frontenac', La Crescent', and 'Prairie Star' were above the minimum levels for commercial winemaking for the parameters, yield, soluble solids content, and pH in at least one location for at least one year of this study. The cultivar 'Traminette' had yield and soluble solids that were above minimum levels, but the pH was below the minimum level for winemaking. The soluble solids content and yield of 'St. Croix' were below minimum levels for commercial production. The cultivar 'Vignoles' had soluble solids content and pH within the desirable range for winemaking, but yield was below commercially viable levels. The cultivar 'Riesling' did not reach minimum levels for commercial wine production in yield, soluble solids content, or pH. During the winter of 2004-2005, the same wine grape cultivars, with the addition of two hybrid cultivars, were analyzed for bud survival under field conditions by visual observation of oxidative browning. The low temperature recorded for the winter was between -27°C and -25°C, depending on site location. In vineyards 3 and 4, where data on bud survival at the end of winter were complete, 'Arctic Riesling' (68%) and 'Leon Millot' (63%) had the highest primary bud survival rate in the respective vineyards. The cultivar which appeared to have the next highest primary bud survival at the end of the winter was 'Traminette' (31%) in Vineyard 3. The lowest primary bud survival rates at the end of winter were observed in the French-American hybrid cultivars 'Vidal' (2%) and 'Vignoles' (7%) and the V. vinifera cultivar 'Riesling' which had 13% bud survival at Vineyard 3 and 0% bud survival at Vineyard 4. At Vineyards 1 and 2, data were incomplete at the end of winter. At these vineyards, midwinter primary bud survival rates of the cultivars 'Louise Swenson', 'Prairie Star', St. Croix', 'La Crescent', and Frontenac' ranged from 56% to 89%. Factors such as winter injury, disease, nutrient imbalances, and cultural practices impaired the yields, fruit quality, or bud survival of some cultivars. Better management of these factors would have a positive impact on wine grape cultivar performance in Vermont.