Shoot growth characteristics following mechanical hedging and high limb pruning in 'Tulare' walnuts on two rootstocks at two spacings.

摘要

Shoot re-growth following mechanical hedging was measured in a 10 year old 'Tulare' walnut orchard planted at two tree spacings on two rootstocks. In addition to the mechanical hedging treatment, high limb pruning, designed to lower overall tree height, was performed on sub-plots each year by selectively removing 1-3 limbs of 5 to 10 cm diameter high in the canopy. The greatest terminal shoot growth occurred in the year following hedging, while the greatest overall growth, including laterals, occurred in the second year following hedging. The number of new branching points formed increased for the second and third year after hedging but decreased by the fourth year. Terminal shoot growth was significantly greater for the wider compared to narrower spaced trees in the first year after hedging and thereafter there were no significant differences. The only impact of the high limb pruning treatments was significantly greater terminal shoot growth for the high limb pruned trees versus the non-high limb pruned trees at the narrow tree spacing. These results suggest that less frequent pruning is likely to increase productivity. In addition, it suggests that cultural practices in the year after hedging have the most potential to control canopy development..