Two management systems were initiated in a 10 year old Juglans regia cv. Hartley orchard planted 8 m. × 8 m. in 1977. Annual dormant selective pruning was practiced for the next 8 years on all trees within one treatment (pruning) compared to dormant severe pruning on alternate temporary trees with no pruning on adjacent permanent trees (thinning). Temporary trees were removed in the thinning treatment in 1985.
Yield, trunk cross sectional area, pruning weight and nut quality factors were evaluated each year from the 5 replicate, completely randomized trial.
Yield and nut quality factors did not differ between the two treatments during the 15 years.
In 1990 the pruned trial was again pruned causing a 20% drop in production (p=.06). With no additional pruning yield returned to slightly above the thinned treatment in 1991.
This trial demonstrates that Hartley walnut trees (terminal bearing habit) continue to produce satisfactory crops under crowded canopy management but a tree thinning program offers other advantages which also should be considered.
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