Is this an overly dramatic post title? Possibly, but I also had fun with it, so we're sticking with it. But good tree care is a serious deal. When properly cared for, a tree can boost property value, provide shade, shelter wildlife, and improve human well-being. Bad management practices, such as topping, can turn an otherwise wonderful tree into a potential safety hazard for many years in the future and kill it in the long run.
What is topping?
According to a Purdue Extension bulletin, topping is "the drastic removal or cutting back of large branches in mature trees. The tree is sheared like a hedge and the main branches are cut to stubs. Topping is often referred to as heading, stubbing, or dehorning." The picture above is one example of topping.
What's so bad about topping trees?
Don't the branches just grow back? People who promote topping will often point to the fact that profuse growth will quickly spring from the stubs. However, this is not good, strong growth. This is the tree's stress response to losing so much canopy at once, and the connections between these new branches and the stronger limbs are very weak. These branches do not form the kind of shape you would expect to see in a tree naturally. In the image on the left you can see that there are dozens of new branches all coming out of the same area. These branches are highly susceptible to failure, and when they fall they could damage persons or property under the tree.
Topping a tree also creates many, many wounds, few (if any) of which will fall at a location on the branch where they can properly seal over. A cut on a tree can never truly heal; it must have new tissue grown over it to form a protective layer as quickly as possible to prevent the invasion of pathogens. When a branch is cut without regard for which areas of tissue are capable of closing off wounds, you will be left with an open gateway for harmful insects and disease. It can take many years for an infection to kill a tree, so if a tree fails five years after being topped, you may not think to link the tree death to the improper pruning years earlier. Read more about good tree pruning practices.
Even if a tree manages to avoid insect or disease infestation from the wound sites, it will be stressed from losing so many branches. Areas of the tree that used to be sheltered will be exposed. The tree will have to use up valuable energy stores from the roots to replace the lost branches.
Why do people top trees?
One of the most common reasons is to control the tree's size. The best way to avoid a size conflict is to pick the right tree for your location (review my earlier post on picking the right plant for the right place). Many shrubs tolerate routine size reductions, but trying to prevent a tree from reaching its mature size is a losing battle that will only end with an unhealthy tree and potential property damage. If you absolutely must keep a tree's size in check, and you aren't interested in removing the tree altogether, crown reduction is a much better option. This technique involves strategically cutting limbs back to major branch unions lower on the tree. We do not recommend attempting this without training, as it is still possible to do a lot of damage if done improperly.
Another reason for less extreme topping is that some people like the tightly sheared look it can produce. Again, picking the right plant can achieve the desired goal without resorting to topping. Hornbeams and Lindens are two families of trees that naturally have a very tight, dense form without intrusive topping and shearing. Both you and your tree will be happiest when it is allowed to grow in its natural form.
If topping is so bad, why do tree companies still do it?
The simple reason is that people don't know better. There is no requirement that tree management companies have any kind of arborist licensing or formal training, so there are so-called professionals that don't know the harm they're doing. There are also companies that may know it's not the best management practice, but if consumers will pay for the service, they will still provide it. For the protection of your trees and your property, never hire a tree company that offers topping as one of its services. When dealing with major tree work, it's always best to work with an insured and bonded company that has at least one ISA (International Society of Arboriculture) Certified Arborist on staff. To find a qualified professional in your area, check out the ISA's online directory.