Alternate-year walnut pruning can boost yields, cut cost

Annual pruning was compared to nonpruning for 8 years and to two alternate-year pruning treatments for 4 years in a mature, full-canopied ‘Ashley’ walnut orchard. Pruning increased light penetration and subsequent nut distribution throughout the canopy. Nut size and percent edible kernel wen? consistently lower in nonpruned trees than in trees pruned annually or biennially. However, annual pruning did not improve yield over that of nonpruned trees because fruitful spurs were removed. Alternate-year pruning resulted in yields comparable to those for nonpruned and annually pruned trees in the year following pruning. Biennially pruned trees yielded more than annually or nonpruned trees during the year pruning was not performed. Alternate-year pruning produced the highest income per acre even when the cost of pruning was considered.