If seeing is believing, then many people must believe that topping trees is an acceptable pruning practice. Even though most tree care professionals disapprove of topping, it seems to be increasing at an alarming rate.
Topping is also known as stubbing, dehorning, heading back, and lopping. But no matter what it's called, it completely disfigures trees by amputating the entire crown.
To many people, topped trees look pruned. In contrast, a properly pruned tree looks so natural that most people may not realize it has been pruned at all. Pruning a tree the right way requires about 30 percent more labor than topping. However, the advantages of good pruning practices are well worth the extra effort. Properly pruned trees live longer and are healthier than topped trees. Fear is often used to sell topping. It seems easy to convince someone that a large tree is apt to fall on their house and kill someone. Many other questionable reasons are also given for such radical butchery.
Unfortunately, almost anyone can top trees. It takes no special training to use a chain saw to remove all the limbs from a tree but most people don't realize the harm this causes. Trees store food in twigs and limbs. Removing them depletes a tree's food reserves. This weakens and stresses the tree. As a result, topped trees are more susceptible to disease and insect attack, and sunscald of the bark.
New shoots produced at the large stub cuts, use sparse food reserves to grow back. These long, straight shoots are weakly attached and break off easily. Branches formed from these shoots will be hazardous throughout the life of the tree. Limbs that regrow on topped trees are more apt to break than those on trees that have been properly pruned.
The large wounds created by topping seldom heal completely. Exposed wood often rots causing weak, hollow limbs. Consequently, previously topped trees often have dead or dying limbs that need to be removed. Topping actually costs more in the long run than proper pruning.
Topping is rarely justified. The best advice is to prune trees only if you have a good reason for doing so. Good reasons include: removal of broken, damaged, diseased, or dead limbs; clearance for safety; or, correction of a structural deformity. Topping should be completely unnecessary if the tree has received early and proper pruning or if the right tree has been planted in the first place.
For large trees near buildings or other targets, it is often safer and less expensive to cut down and replace them with low growing trees. Hazard trees that are in danger of falling and damaging property or injuring people should be removed as soon as possible.
What can you do to stop topping? Some people are taking steps to protect the trees in their communities. Communities can pass tree ordinances that prohibit topping street trees and prohibit planting of large, weak-wooded trees, like Siberian elms and silver maples. Requiring arborists and tree workers to be certified also helps. It may also help if we tell our friends and neighbors that topping is harmful.
For more information, consult the ISU Extension publications entitled "Topping---Tree Care or Tree Abuse?" (Pm-1371), "Street Trees for Iowa" (Pm-1429e), and "Low-Growing Trees for Urban and Rural Iowa" (Pm-1429d). These and many other publications on trees are available from your local county Extension office.
This article originally appeared in the April 27, 1994 issue, p. 54.