Pruning strategies for restructuring top‐dominant central leader ‘Granny Smith’ apple trees

Abstract

Abstract Eighteen‐year‐old, top‐dominant central leader trees of ‘Granny Smith’ apple (Malus domestica Borkh.) were restructured during the 1987 and 1988 dormant seasons into either palmette central leader (initially) or pyramid central leader forms. In the palmette form, pruning was restricted to the total removal of the uppermost east‐ and west‐facing fruiting scaffolds in 1987, and the shortening of all middle scaffolds and the upper north‐facing scaffold in 1988. In the pyramid form, major scaffold limbs were subjectively removed or shortened to reestablish the desired pyramid shape over the two dormant seasons. Both forms were also renewal pruned annually to totally remove pendant fruiting laterals and spur‐bearing wood over 4 years old. In addition, unmodified top‐dominant trees that were either renewal pruned or containment pruned (primarily heading cuts) were maintained for comparison with the restructuring treatments. The restructuring treatments resulted in improved light penetration to the lowe...