|Objectives of Pruning Shade Trees|
By David Hubbard
I love my trees and want to do the right things to take care of them. I am told they need to be pruned. Can you tell me if I really need to do this or not?
According to Dr. Ed Gilman, who does tree research at the University of Florida, there are three main consequences of not conducting a regular pruning program. The consequences are 1) development of low aggressive limbs, 2) formation of co-dominant stems and 3) development of defects like included bark and dead branches. Limbs allowed to grow for some time often become large. They often over-extend or may droop under their own weight and have to be removed later leaving a large pruning wound. Removal of large branches and those more than about half the trunk diameter is more likely to initiate decay than removal of smaller branches. Formation of co-dominant stems and defects such as included bark can lead to increased risk of failure. Pruning can help treat and avoid some of these problems.
Gilman says it is important to establish the objective for pruning before starting. He suggests following the objectives and explanations below as a possible plan.
1) Reduce risk of failure: Reduce risk by establishing a structural pruning program begins at planting and carries through the first 25 years. This program should be designed to create structurally sound tree architecture that will sustain the tree for a long period. Medium-aged and mature trees can be cleaned, thinned, reduced, raised or restored to manage risk. Some structural pruning can be conducted on these older trees as well.
2) Provide clearance: Growth can be directed away from an object such as a building, security light or power line by reducing or removing limbs on that side of the tree. Regular pruning is required to maintain the artificial clearance. Canopy reduction or pollarding helps maintain a tree smaller than it would be without pruning. Utility pruning keeps limbs clear of overhead wires and other utility structures. The crown can be raised to provide clearance by shortening low branches so those toward the middle and top of the tree are encouraged to grow.
3) Reduce shade and wind resistance: A lawn, ground covers or shrubs can receive more sunlight when live foliage is removed from the canopy. Thinning, reducing and pollarding can be used to accomplish this.
4) Maintain health: Maintain health by cleaning the canopy, especially in medium-aged and mature trees. Removing dead, diseased and rubbing branches in the canopy of young trees may be a lesser priority. Root pruning can also be used to reduce the rate of spread of certain vascular disease, like oak wilt and Dutch elm disease.
5) Influence flower or fruit production: The number and/or size of flowers or fruit can be influenced by pruning. Fruit size can be increased on certain plants like peaches by removing some of the developing fruit or flowers. Flower cluster size can be increased on crape myrtle and some other trees by making heading cuts on many branches. Fruit production can be eliminated by removing flowers.
6) Improve a view: A view can be enhanced or opened by removing live branches. This pruning can include thinning, reducing, pollarding and raising.
7) Improve aesthetics: A tree can be pruned to make it look more appealing. Cleaning, reducing (shaping), thinning, pollarding and restoring can be used to meet this objective.
I think with what you’ve read above, you can see the importance of pruning. I hope this helps both you and your trees. Good Luck!
David Hubbard is a Regional Extension Agent with the Alabama Cooperative Extension System.