A Topped Tree Is the Devil’s Playground
Maria Gulley is the horticulturist at Gardens of Growth, a full service landscape design, build and maintenance firm, where she also manages the company blog. She guests blogs about her experience volunteering as a Tree Tender for KIB and her passion for the value of urban trees and greenspaces, and enhancing our communities.
I know it’s a dramatic post title, but I had fun with it, so that’s what I’m sticking with. Melodramatic titles aside, good tree care is a serious deal. When properly cared for, a tree can boost property value, provide shade, shelter wildlife, and even 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.
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." (read the full bulletin here) The picture above is one example of topping.
What's so bad about a topped tree? Don't the branches just grow back? People who defend topping will often point to the fact that lots of new growth will quickly spring from the stubs. However, this is not good, strong growth. This is the tree's stress response to these improper pruning cuts, and the connections between these new branches and the stronger limbs are very weak. These new 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 heal over. A cut on a tree can never truly heal; the tree must grow new tissue over it to form a protective layer as quickly as possible to prevent the invasion of insects and diseases. When a branch is cut without regard for which cell zones 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 infestation 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. Even if a tree manages to avoid insect or disease infestation from the wound sites, it will be left stressed from losing so much canopy. 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. 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, a frustrated homeowner, 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 to the tree with this method if done improperly. Another reason people give to defend less extreme topping is that they like the tightly sheared look it can produce. Again, picking the right plant can achieve the desired goal without resorting to topping or shearing. 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, then 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 significant tree work, it's always best to work with an insured and bonded company that has at least one certified arborist on staff. To find a qualified professional in your area, check out the International Society of Arboriculture's online directory.