The Vertical Axis System: A Training Method for Growing Apple Trees
New apple cultivars often command higher prices than some older cultivars such as Jonathan, Red and Golden Delicious. If a grower can bring a new apple into production while it is in demand, a new variety can be more profitable than producing older cultivars. High-density orchard systems (greater than 500 trees per acre), such as the vertical axis system, can be used to produce fruit in the second or third year after planting. In contrast, low-density orchard systems (150 to 200 trees per acre) generally require five years to come into production.
Intensive production systems such as the vertical axis system have additional benefits other than early production of fruit. Pruning and harvesting costs are reduced due to the small size of the trees. Less spray material is also applied to the dwarf trees. But there are disadvantages as well. The cost of establishment, which includes installing a trellis system, is greater. Also, more intensive management techniques are required, since disease and insect pests can spread rapidly among closely planted trees.
In the vertical axis system, the trees are trained and maintained in a narrow pyramidal shape with a dominant central leader to maximize light penetration within the tree canopy. The central leader is trained to grow vertically to a height of about 10 feet. In this system, few pruning cuts are made during the first three years after planting until the trees have begun to grow together. Thereafter, lateral branches are periodically renewed by cutting into 2-year-old or older growth. Trees are supported by a trellis, consisting of a conduit or a wooden post at each tree with at least one wire connecting the tops of the posts