Articles
Mechanical pruning trial after five years in ‘Improved French’ prune in a California commercial orchard
Article number
1450_16
Pages
117 – 122
Language
English
Abstract
The California prune industry historically relies on hand pruning to thin fruitwood, improve fruit size, reduce alternate bearing, and control tree size and shape.
Both the high cost and limited availability of skilled labor have increased the interest in mechanical pruning.
An experiment was established to evaluate timing and severity of mechanical hedging compared to a hand pruned control.
The severe mechanical pruning treatment consisted of hedging four sides of the canopy and topping (boxing) and the moderate treatment was hedged two sides of the canopy every year.
These treatments were conducted either in early spring (May) or postharvest (October). After five years, cumulative yields of marketable dry fruit (size A + B screen) were not significantly different between treatments, albeit there was a numerical trend of trees subjected to hedging on both sides yielding numerically more than those subjected to box hedging.
In terms of fruit size, in only one of the five years (2022) was there a significant difference, with a smaller percentage of marketable A and B screen fruit in the boxed in fall treatment (68%) compared to the hand pruned control (92%). These findings underscore the robust adaptability of the trees and suggest that the timing and severity of hedging interventions had a minimal impact on the overall fruit yield and quality.
While no significant yield differences were detected, mechanical boxing and hedging both sides projected yearly 805 and 1052 savings ( ha‑1), respectively, compared to costs of hand pruning.
Periodic hand pruning in mechanically hedged trees (for example every four years) may still be beneficial.
The long-term effects of mechanical pruning on disease incidence and orchard longevity still need to be investigated.
Both the high cost and limited availability of skilled labor have increased the interest in mechanical pruning.
An experiment was established to evaluate timing and severity of mechanical hedging compared to a hand pruned control.
The severe mechanical pruning treatment consisted of hedging four sides of the canopy and topping (boxing) and the moderate treatment was hedged two sides of the canopy every year.
These treatments were conducted either in early spring (May) or postharvest (October). After five years, cumulative yields of marketable dry fruit (size A + B screen) were not significantly different between treatments, albeit there was a numerical trend of trees subjected to hedging on both sides yielding numerically more than those subjected to box hedging.
In terms of fruit size, in only one of the five years (2022) was there a significant difference, with a smaller percentage of marketable A and B screen fruit in the boxed in fall treatment (68%) compared to the hand pruned control (92%). These findings underscore the robust adaptability of the trees and suggest that the timing and severity of hedging interventions had a minimal impact on the overall fruit yield and quality.
While no significant yield differences were detected, mechanical boxing and hedging both sides projected yearly 805 and 1052 savings ( ha‑1), respectively, compared to costs of hand pruning.
Periodic hand pruning in mechanically hedged trees (for example every four years) may still be beneficial.
The long-term effects of mechanical pruning on disease incidence and orchard longevity still need to be investigated.
Publication
Authors
R. Rosecrance, B. Wheeler-Dykes, L. Milliron, F.J.A. Niederholzer, C. Reyes, K. Caldera, N.J. Ott
Keywords
Prunus domestica, hand pruning, hedging, topping, yield, fruit size
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