January is a good time to consider winter pruning of your trees. Links and information provided is mostly directed to fruit producing trees, but, this information is also valuable in pruning shade and ornamental trees and shrubs.
Pruning vs. Training – Historically fruit tree form and structure have been maintained by pruning. Tree training however is a much more efficient and desirable way to develop form and structure.
Pruning is the removal of a portion of a tree to correct or maintain tree structure. Training is a relatively new practice in which tree growth is directed into a desired shape and form. Training young fruit trees is essential for proper tree development. It is better to direct tree growth with training than to correct it with pruning. Pruning is most often done during the winter, commonly referred to as dormant pruning.
Training includes summer training, summer pruning as well as dormant pruning. The goal of tree training is to direct tree growth and minimize cutting.
Dormant Pruning vs. Summer Pruning Trees respond very differently to dormant and summer pruning. Dormant pruning is an invigorating process. During the fall, energy is stored primarily in the trunk and root system to support the top portion of the tree. If a large portion of the tree is removed during the winter, while the tree is dormant, the tree’s energy reserve is unchanged. In the spring, the tree responds by producing many new vigorous, upright shoots, called water sprouts, which shade the tree and inhibit proper development. Heavy dormant pruning also promotes excessive vegetative vigor, which uses much of the tree’s energy, leaving little for fruit growth and development.
Historically much of the vigorous upright vegetative growth has been removed during the dormant season. Heavy dormant pruning results in a yearly cycle with excessive vegetative growth and little or no fruit production. Timing of dormant pruning is critical. Pruning should begin as late in the winter as possible to avoid winter injury. Apple and pecan trees should be pruned first, followed by cherry, peach, and plum trees. A good rule to follow is to prune the latest blooming trees first and the earliest blooming last. Another factor to consider is tree age. Within a particular fruit type, the oldest trees should be pruned first. Younger trees are more prone to winter injury from early pruning.
Summer pruning eliminates an energy or foodproducing portion of the tree and results in reduced tree growth. Pruning can begin as soon as the buds start to grow, but it is generally started after vegetative growth is several inches long. For most purposes, summer pruning should be limited to removing the upright and vigorous current season’s growth; only thinning cuts should be used. To minimize the potential for winter injury, summer pruning should not be done after the end of July.
Types of Pruning Cuts Thinning Cutting removes an entire shoot back to a side shoot. Thinning cuts do not invigorate the tree in comparison to some of the other pruning cuts.
Heading Cutting removes only the terminal portion of a shoot. This type of cut promotes the growth of lower buds as well as several terminal buds below the cut. When lateral branches are headed into oneyearold wood, the area near the cut is invigorated. The headed branch is much stronger and rigid, resulting in lateral secondary branching. Older trees can be held in their allotted space by mold and hold cuts, which are devigorating heading cuts made into two year old wood. Young trees and branches where heading cuts are made will be referred to as headed.
Bench Cutting removes vigorous, upright shoots back to side branches that are relatively flat and outward growing. Bench cuts are used to open up the center of the tree and spread the branches outward. This is a major cut and should only be used when necessary.
When making pruning cuts it is important to use techniques that will allow the cut surface to heal quickly. Rapid healing minimizes the incidence of disease and insect infection. Pruning cuts should be flush with the adjacent branch without leaving stubs. Also, when large horizontal cuts are made, they should be slightly angled so that water does not set on the cut surface, allowing the growth of rot and disease organisms.
Many compounds are available as wound dressing or pruning paints. But the best treatment is to make proper pruning cuts and allow the tree to heal naturally. If preferred, tree paints and wound dressing may be used for aesthetic reasons, but they will not promote healing.
Central Leader Training, Apple, Cherry, Pear, Pecan, Plum A central leader tree is characterized by one main, upright trunk, referred to as the leader. Branching generally begins on the leader 24 to 36 inches above the soil surface to allow movement under the tree. The first year, 3 to 4 branches, collectively called a scaffold whorl, are selected. The selected scaffolds should be uniformly spaced around the trunk, not directly across from or above one another. Above the first scaffold whorl, leave an area of approximately 18 to 24 inches without any branches to allow light into the center of the tree. This light slot is followed with another whorl of scaffolds. Alternating scaffold whorls and light slots are maintained up the leader to the desired maximum tree height.
The shape of a properly trained central leader tree is like that of a Christmas tree. The lowest scaffold whorl branches will be the longest and the higher scaffold whorl branches will be progressively shorter to allow maximum light penetration into the entire tree.
Developing a Central Leader Trained Tree At Planting Fruit trees are frequently purchased as whips, which are unbranched trees ranging from 1/2 to 3/4 inch diameter. The tree should be planted in early winter with the graft union 2 inches above the soil surface. Just before the buds start to grow in the spring, the tree should be headed, or cut off, at 30 to 34 inches above the soil surface. The height at which the tree is headed depends upon where you want the first whorl of branches. Once the tree is headed, permanent branches will be selected from buds growing within 4 to 12 inches below the heading cut.
North Carolina State Ag Extension Service