Gary L. Main

An Investigation of Training System, Pruning Severity, Spur Length, and Shoot Positioning on Cynthiana/Norton Grapes

This five-year study evaluated the effects of Geneva double-curtain (GDC) and single-curtain (SC) training systems, 30+10 and 60+10 balanced pruning severities, 3- and 6-node spur lengths, and shoot positioning on yield and fruit composition of Arkansas-grown Cynthiana/Norton, aestivalis-type grapes. The GDC-trained vines had a 46% higher yield than SC-trained vines, but yield per m/cordon was lower for GDC-trained vines. Additional yield on GDC-trained vines appeared to come from noncount shoots. Vine dormant prunings, number of retained nodes, and cluster weights were similar between training systems. Juice pH was lower on GDC-trained vines; other measures of fruit composition were similar between training systems. Pruning to a 60+10 severity increased the number of retained nodes and increased yield and clusters per vine as compared to 30+10 but did not affect fruit composition. There was no difference in yield on vines pruned to 3- or 6-node spurs and there was no difference in fruitfulness associated with node position along the spur. Pruning to 3-node spurs increased the percentage of soluble solids while maintaining slightly greater vine vigor than pruning to 6-node spurs. Shoot positioning did not affect vine yield but did reduce vine vigor and lower fruit pH. Shoot positioning should be considered based on individual vineyard vigor and production methods.