COMPARISON OF PRUNING TECHNIQUES TO INVIGORATE LOW-VIGOR ALMOND TREES

Abstract

Some precocious almond varieties often produce little vegetative growth once they reach full maturity. A pruning trial was established using 11 year old `Harvey' trees that were healthy but making little or no new growth. The four treatments were: 1) severe heading or dehorning trees to six foot in height (first year only), 2) heading one third of the tree for three years, 3) making 20 small heading cuts all over the tree each year, and 4) normal thinning cuts (or control). All heading treatments caused more shoot growth than did the conventional thinning cuts (or control). The dehorning treatment (#1) responded with the most vigorous growth but much lower yields during the next two years compared to the control (#4). Yields were comparable between the two treatments during years three to five however. The heading treatments #2 and #3 had comparable yields with the control by the second year. They also showed more shoot growth. Tree yields from treatment #2 tended to lag below treatment #3 and the control, even though they were statistically the same. This trend may indicate that three years of moderately severe pruning is too much. Treatment #3 may be the best technique for invigorating healthy low vigor trees while minimizing yield losses, but will be the most expensive.