Effects of balanced pruning severity on traminette (Vitis spp.) in a warm climate

Canopy architecture, yield components, fruit composition, vine size, Ravaz index, and midwinter primary bud cold hardiness of Traminette grapevines were measured in response to balanced pruning treatments of 20, 30, or 40 nodes retained for the first 454 g of dormant pruning weight and an additional 10 nodes for each additional 454 g in 2006 and 2007. As pruning severity increased from 40 + 10 to 20 + 10, shoots per hectare decreased and the distance between shoots increased. Leaf area per vine and leaf layer number showed a linear increase as pruning severity decreased. As the pruning severity decreased, the number of clusters harvested per vine and yield increased. Fruit composition was not affected by pruning severity. Vine size and leaf area per unit of fruit weight were not affected by the treatments, but Ravaz index (weight of fruit per weight of pruned wood) increased linearly as pruning severity decreased in 2007. In 2007, as pruning severity increased, more nodes were mature by late fall and buds were more cold hardy in midwinter. Results suggest that in the absence of any measurable effects of disease incidence or adverse effects on fruit composition, the 40 + 10 treatment should be used in the lower Midwest of the United States, as it optimized yield with only a slight decrease in primary bud cold hardiness.