Hello my dear Gardening Friends,

It’s that time of year when people start to shape their trees, so I’d like to talk to you about tree pruning. So many people ask, “can I just cut the top off my ‘whatever’ tree?” Topping is the most harmful of tree pruning practices. We listen to seminars, read books that tell us how harmful this is - and still we ask the same question, or people just go ahead and do it regardless.

What exactly is “topping?” It is the indiscriminate cutting back of tree branches to stubs, or lateral branches that are not large enough to become the terminal branch. You will hear other names for this bad practice, such as “heading,” “tipping,” “hatracking,” and “rounding over.” If someone comes to trim your trees and suggests any of the former, do not let them anywhere near your precious trees!

The most common reasons they will give to reduce the size of the tree is that it has grown too large for your property, or if you think that it is too tall and is posing a hazard. Topping is not a good method of reducing the height, and most certainly does not reduce any hazardous problems. In fact, topping will make a tree more dangerous in the long run.

Topping often removes 50-100% of the leaf bearing crown of a tree. Since the leaves are the “food factories,” of a tree, this can actually temporarily starve a tree. Severe pruning triggers a sort of survival mechanism, which activates latent buds, forcing the rapid growth of multiple shoots below each cut. The tree needs to put out a new crop of leaves as soon as possible. If the tree does not have the stored energy reserves to do this, it will seriously weaken and may die. A stressed tree is more vulnerable to insect and disease infestations. Large open pruning wounds expose not only the sapwood, but also the heartwood to attack. The tree may lack sufficient energy to chemically defend its wounds against any invasion. In fact, some insects and birds are attracted to stressed trees by chemical signals these wounded trees give off.

The preferred place to make a pruning cut is just beyond the branch collar at the point of attachment. The tree is biologically equipped to close such a wound, provided that the tree is healthy and the cut not too large. Cuts made along a limb, between lateral branches, create stubs with wounds that the tree may not be able to close. The exposed wood tissues begin to decay. Normally a tree will “wall off” or compartmentalize the decaying tissues. Few trees can defend against the multiple severe wounds caused by “topping.” The decay organisms are given a free path to move down through the branches.

Not only disease but also sunburn will take its toll. Branches within a tree's crown produce thousand of leaves to absorb the 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 to the tissues beneath the bark. This leads to cankers, bark-splitting and even death to some of the branches.

The survival mechanism that causes trees to produce multiple shoots below each topping cut comes at great expense to the tree and pocket. These shoots develop from 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 a year, in some species). Unfortunately, these shoots are very prone to breaking - especially during windy conditions. The irony of all this is that while the goal was to reduce the tree's height to make it safer, it has been made more hazardous than ever.

The natural branching structure of a tree is a biological wonder. Trees form a variety of shapes and growth habits, all with the same object of presenting their leaves to the sun. Topping removes the ends of branches, leaving ugly stubs and destroying the natural form of a tree. Without leaves (up to six months of the year) a topped tree appears disfigured and mutilated. With leaves it is a dense ball of foliage lacking its simple grace. A tree that has been topped can never fully regain its natural form.

Topping is expensive, and the cost is not limited to what the perpetrator is paid. If the tree does survive, it will require pruning yet again within a few years. It will either need to be reduced again, or storm damage will have to be cleaned up. If the tree dies, it will have to be removed. Topping is actually a high maintenance pruning practice.

There are even some hidden costs. One, of course, is the reduction in property value. Healthy, well maintained trees can add 10-20% to the value of any property (provided the new owner likes trees). Disfigured, topped trees should be considered an impending expense. Another potential cost is one of liability, as topped trees are prone to breaking and are hazardous. Since topping is considered to be an unacceptable pruning practice, any damage caused by branch failure of a topped tree may lead to a finding of negligence. We are of course speaking of large old trees. I understand that a large area of maple trees was “harvested” near Warsaw and the resulting mess was considered a hazard.

What do we do? For there are times when a tree must be reduced in height or spread - providing clearance for hydro (utility) lines, for example. There are recommended techniques for doing this. If practical, branches should be removed as far back as possible 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 good rule of thumb for this is to cut back to a lateral that is at least 1/3rd the diameter of the limb that is being removed.

This method of branch reduction helps to preserve the natural form of the tree. However, if large cuts are necessary the tree may not be able to heal itself and perhaps the best solution is to have the tree removed and a new one of more appropriate size and species planted in its place.

Pruning large trees can be very dangerous. If this work involves working above the ground, or using power equipment (I have seen my cousin climbing a tree with a chain saw running!), I would suggest that you hire an arborist. This way, you will get the correct information as to what type of pruning is required to improve the shape, health, appearance and safety of your trees. Make sure that whoever you use provides a trained service crew, with the required safety equipment and liability insurance.

If you do hire someone, always ask if they belong to an accredited organization. Also ask for Proof of Insurance and lists of references (do not be afraid to ask for one and do check with a couple of the names). Make sure that you avoid using any tree company that advertises topping as a service provided. Knowledgeable arborists know that topping is harmful to trees and not accepted practice. Also be wary of any company that use tree climbing spikes for climbing trees about to be pruned; climbing spikes can damage trees, and their use should be limited to trees that are being removed.