Pruning Height and Selective Limb Removal Affect Yield of Large 'Hass' Avocado Trees

Abstract

Avocado (Persea americana Mill. cv. Hass) trees were pruned over 3 years at either 4 or 6 m in height by removing or heading back selected limbs. Yields were compared with those from control trees with no pruning in the upper canopy. All trees had similar crop loads before pruning. Trees were at 9 × 10-m spacing and were 8 years old when first pruned. Fruit yields were recorded for 2 years before the first pruning and then in each year of pruning. In the final year, trees were harvested in four height zones: 0-2m; 2-4 m; 4-6 m; and >6 m. Cumulative yields over 3 years were similar on 6-m and control trees, but were less on 4-m trees due to the large volume of fruiting canopy removed in the first pruning. The height of the main fruiting zone was lowered on the 4-m trees, with yields in the 2-4-m zone similar to those in the 4-6-m zone of the control trees. Pruning to reduce the number and length of scaffold branches increased fruit yields on the remaining scaffolds without reducing fruit size. Results are discussed in terms of harvest efficiency and the benefits of small tree orchard systems.