Horticulture Principles and Practices

3. In the third and subsequent years, the central leader is encouraged to maintain
its dominant position and the development of secondary branches is controlled.
4. Spreaders may be necessary to widen narrow crotch angles between secondary
branches and the trunk.
19.10.2 DEVELOPING TREE FORM
Ornamental trees take time to develop their form, and therefore growers should not be
overly concerned about unattractive forms in the early years of their growth. It is important
that about 30 percent of the plant’s foliage be located in the lower half of the tree during
the first three to four years of growth. The lower branches are progressively removed
as the plant grows to establish a desirable clearance beneath the limbs. By adopting this
strategy, the tree develops a straight, strong, tapered, and attractive trunk. Ornamental
trees can be trained to have one of several forms, described in the following sections.
Feathered Form
The goal of training a feathered tree form is to maintain a simple main stem with well-spaced
laterals for good balance. Once a central leader has been identified, crossing laterals should
be pruned by cutting them to the main stem (Figure 19–12). A desirable clearance is established
beneath the limbs by removing the lowest branches. If staking is needed, a low stake
allows the main stem to flex for strength development. In the second and subsequent years,
regrowth at the stem base is pruned along with any vertical shoots that compete with the central
leader. Crossing branches are removed as they occur. Once adequate strength has been
developed in the trunk, the stake should be removed. This system of training is the easiest
to perform. Evergreen trees are commonly trained to have a feathered form.
Standard Form
A standard tree form can develop naturally. There are two variations of this form. The
central leader standard is a modification of the feathered form but with more clearance
beneath the limbs (Figure 19–13). Laterals on the lowest one-third of the tree are pruned
in stages. In the first year, laterals in the top one-third are left untouched, with the exception
of dead branches. Those in the midsection are shortened by half, and those in the
lower one-third are removed completely. In the next two years, the pattern in year one is
repeated, except that the laterals that were shortened in the previous year are removed.
In addition, any existing cross branches are removed in the top section of the tree. This
process continues until a desired length of clear stem is attained.
Prune
Prune
FIGURE 19–12
Feathered tree form development.
FIGURE 19–13
Development of a standard tree form.
19.10 Training and Pruning Ornamental Trees 581