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78 W i n e s & V i n e s A P R i L 2 0 1 4 WineEast V idal Blanc, or Vidal (Ugni Blanc x Rayon D'Or), is a white grape variety that belongs to the group of highly productive hybrids that tend to overcrop, which results in reduced growth and lower fruit and wine quality. Vidal's propensity to overcrop has been attributed to its high bud fruitfulness and large clusters. Research has shown that the best way to manage this variety is with bal- anced pruning and cluster thinning—also referred to as "balanced cropping," a term coined by Dr. Stan Howell from Michigan State University. Vidal has been widely planted in eastern and midwestern states due to its many positive attributes: moderate cold hardiness (more cold hardy than Vitis vinifera variet- ies), spring frost avoidance (due to late bud break), bunch rot resistance and especially its versatile and desirable wine style and quality. In the northeastern United States and Canada, Vidal acreage has expanded since the early 1990s because of its use in ice wine production. Its high yields, thick berry skin, high acidity and fruitiness make it particularly suited for ice wine. Grapes for ice wine production are left to hang on the grapevines long past their typical commercial maturity and are not harvested until they freeze on the vine at an air tem- perature of 18°F or lower. Unlike in warmer regions, "hang time" in the cold regions of the northeast and Canada results in ideal conditions for ice wine production. However, Vidal growers have always been concerned about the impact of "hang time" Winter Survival of Vidal Blanc Vines for Ice Wine Production Study investigates the effect of cluster thinning and pruning on crop level By Imed Dami Grapegrowing Wine East HIGHLIGHTS • Vidal growers in eastern and midwestern states have always been concerned about the impact of "hang time" on vines for ice wine production. • This article describes a study concerning the impact of different crop levels and harvest dates on yield, fruit quality and primarily the winter hardiness of Vidal grapevines. • no adverse impact was found on bud cold-hardiness when balanced pruning was applied in tandem with cluster thinning to avoid overcropping. Vidal Blanc clusters are left to hang for ice wine production and typically are picked in December, when temperature drops to 18 o F.