Written by Richard Thompson
Homeowner associations often deal with tree issues in the form of view blocking or overcrowding as they age and grow. Tree topping is sometimes used to address the view issue. But tree topping is perhaps the most harmful tree pruning practice known. Yet despite years of explaining its harmful effects, it remains a common practice. While the object is to reduce size or improve view, there are alternatives that achieve the same goals while protecting the health of the tree.
A stressed tree is more vulnerable to insect and disease infestations. Large, open pruning wounds expose the sapwood and heartwood to attack. The tree may lack sufficient energy to chemically “defend” the wounds against invasion. Some insects are actually attracted to stressed trees by chemical signals.
Topping Can Lead to Sunburn. Branches within a tree’s crown produce thousands of leaves to absorb sunlight. When the leaves are removed, the remaining branches and trunk are suddenly exposed to high levels of light and heat. The result may be sunburn of the tissues beneath the bark. This can lead to cankers, bark splitting and death of some branches.
Topping Creates Hazards. The survival mechanism that causes a tree to produce multiple shoots below each topping cut comes at great expense to the tree. These shoots develop from buds near the surface of the old branches. Unlike normal branches that develop in a “socket” of overlapping wood tissues, these new shoots are only anchored in the outermost layers of the parent branches. The new shoots grow very quickly, as much as 20 feet in one year, in some species. Unfortunately, the shoots are very prone to breaking, especially during windy conditions.
Topping Makes Trees Ugly. The natural branching structure of a tree is a biological wonder. Trees form a variety of shapes and growth habits, all with the same goal of presenting their leaves to the sun. Topping removes the ends of the branches, often leaving ugly stubs. Topping destroys the natural form of a tree. Without the leaves (up to six months of the year in temperate climates) a topped tree appears disfigured and mutilated. With the leaves, it is a dense ball of foliage, lacking its simple grace. A tree that has been topped can never regain its natural form.
Alternatives to Topping. There are times when a tree must be reduced in height or spread. Providing clearance for utility lines is an example. There are recommended techniques for doing this. If practical, branches should be removed back to their point of origin. If a branch must be shortened, it should be cut back to a lateral that is large enough to assume the terminal role. A rule of thumb for this is to cut back to a lateral that is at least 1/3 the diameter of the limb being removed. This method of branch reduction helps to preserve the natural form of the tree. Sometimes the best solution is to remove the tree and replace it with a species that is more appropriate for the site.
If pruning involves working above the ground, or using power equipment, it is best to hire a professional arborist. An arborist can determine what type of pruning is necessary to improve the health, appearance and safety of your trees. A professional arborist can provide the services of a trained crew, with all of the required safety equipment and liability insurance.
A couple of closing caveats. Avoid using any tree company that advertises topping as a service provided. Hire only a trained arborist. Arborists know that topping is not an accepted practice. Pruning work should be accomplished by free climbing, ladders or lift equipment. Climbing spikes can damage trees, and their use should be limited to trees that are being removed. And never, never, never top your trees.