Tree surgery is the care of trees, chiefly by pruning, bracing, and removing dead or dying branches. Professional tree surgeons are known as arborists. Arborists not only work with branches, but they also apply pesticides to protect trees from insects and diseases. In addition, they may recommend or apply fertilizer to improve the trees’ overall health. Many communities employ arborists to care for trees in parks and recreation areas.
Pruning helps individual trees develop and maintain a strong structure. Proper pruning begins on a young tree and continues every few years throughout the tree’s life. To properly prune a branch, an arborist or gardener must first locate the branch collar, a swelling at the point where the branch is attached to the trunk. All pruning cuts should be made on the outside of the branch collar. Such cuts will soon heal properly without any wound dressing, such as grafting wax or pruning paint.
For large branches, arborists and gardeners use the three-cut method of pruning. They first make a cut on the underside of the branch, 6 to 18 inches (15 to 46 centimeters) from the trunk. The undercut should penetrate at least one-third of the branch’s diameter. Pruners make the second cut on the top side of the branch, slightly farther from the trunk than they made the first cut. The branch will then snap off and a stub will remain. The third cut, made at the branch collar, removes the stub. Pruners should hold the stub while cutting it off, and they should make sure this final cut does not tear the bark from the trunk.
Narrow-angled crotches, where the tree divides into two branches, may cause trouble because they have a tendency to split. Arborists use a procedure called bracing to prevent splitting. They insert a metal rod through the branches that form the narrow-angled crotch. The rod does not injure the tree because it passes through only a small section of the cambium, a layer of living tissue between the wood and bark. Arborists bolt each end of the rod to prevent the branches from shifting.
Gardeners should completely remove diseased or dead branches as soon as possible after detecting them. However, do not attempt to remove decay in the tree’s cavities. Attempts to chisel away rotten wood often spread the decay.
See also Pruning ; Tree (Caring for the tree) .
