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One-year-old `Concord' grapevines (Vitis labruscana Bailey) were fertigated with 0, 5, 10, 15, or 20 mm nitrogen by using a modified Hoagland's solution for 8 weeks during active vine growth in summer. Half of the vines at each N concentration were sprayed with 3% foliar urea twice in late September while the rest served as controls. After natural leaf fall, all the vines were overwintered in a cold room (2 to 4 °C). Four vines from each treatment were destructively sampled before budbreak for reserve N and carbohydrate analysis. The remaining vines were supplied with either no N or sufficient N (10 mm N) from 2 weeks before bloom to 1 month after bloom. All the vines were destructively harvested at 1 month after bloom. Total amount of N in dormant vines increased with increasing N fertigation concentration. Total nonstructural carbohydrates (TNC) increased with increasing N fertigation concentration from 0 to 10 mm, and then leveled off with further rises in N supply. Foliar urea application increased total N but decreased TNC of dormant vines at each given N fertigation level. When no N was provided during the regrowth period, vine total leaf area, fruit yield, and total dry weight increased with increasing N supply from fertigation the previous year. Vines sprayed with foliar urea the previous fall produced a larger total leaf area, a higher yield, and a higher total vine dry weight at each given N fertigation concentration. Providing vines with sufficient N during the regrowth period significantly increased total leaf area, fruit yield, and vine total dry weight across the previous N fertigation concentrations, but vines sprayed with foliar urea still had a larger leaf area, a higher yield, and a higher total vine dry weight at each given N fertigation concentration. Therefore, we conclude that both vegetative growth and fruiting of young `Concord' vines are largely determined by reserve nitrogen, not by reserve carbohydrates, and that current-season N supply plays a very important role in sustaining vine growth and development, especially fruit growth.

Four pruning techniques were evaluated from 1999 to 2003 in a commercial ‘Concord’ (Vitis labruscana) vineyard in Westfield, NY. Manual pruning, mechanical pruning with manual pruning follow-up, mechanical pruning with fruit thinning, and minimal pruning with fruit thinning averaged a 2.4-fold difference in retained nodes per vine. Treatments with crop adjustment required fruit thinning in 3 of 5 years to maintain an acceptable crop size. Manually pruned vines, mechanically pruned vines with manual follow-up pruning, and mechanically pruned vines with crop adjustment had similar yields, juice soluble solids, lignified periderm, juice color, juice titratable acidity, and juice pH in 4 of 5 years. Minimally pruned vines tended to have slightly higher yield and lower juice soluble solids, color, and titratable acidity in 3 of 5 years. Pruning system cost estimates indicated a 56% and 80% cost reduction per acre when comparing manual pruning with mechanical pruning plus manual follow-up or mechanical pruning plus mechanical fruit thinning, respectively. These results support two commercially acceptable and sustainable pruning management options for New York ‘Concord’ grape production.