Crop Load Management in Concord Grapes Using Different Pruning Techniques

Abstract

Effects of mechanical pruning and crop adjustment on Concord vine productivity were studied over a five-year period (1997 to 2001) in two mature vineyards in eastern Washington. Data showed that vines could sustain considerably higher yields than are achieved by balance pruning. Balance-pruned vines consistently produced relatively low yields with only marginally improved fruit composition, but fruit could be harvested somewhat earlier. Large, mechanically pruned single-wire or double-curtain-trained vines produced heavy crops and attained satisfactory fruit composition and shoot lignification in both warm and cool seasons. On average, mechanically pruned vines produced over 9 t/ha more fruit than balance-pruned vines. Yields of vines with fixed-node pruning (130 nodes) or mechanical pruning with crop adjustment were similar and 4.6 t/ha greater than yields of balance-pruned vines. Crop adjustment following mechanical pruning reduced yields but did not improve yield variation, fruit composition, and shoot lignification and therefore was unnecessary in all but the heaviest cropping season (1997). Yields for all pruning treatments varied almost in parallel from season to season, and the influence of pruning method on yield, fruit composition, and shoot lignification was less important than seasonal effects. There was no evidence of vine decline and alternate or biennial bearing due to overcropping of lightly pruned vines.