As an arborist I have frequently been asked to “top” people’s trees. People want their trees topped for several reasons: safety concerns, vista pruning, aesthetics or height reduction. This request prompts a conversation about the practice of tree topping and the hazards associated with it.
Topping a tree is the practice of removing tree tops or pieces of the canopy while leaving stubs or branches that are too small to assume the role of a terminal leader. Probably the most common place to observe a topped tree would be underneath a utility wire. These trees are topped in order to prevent them from interfering with the electric grid and not necessarily pruned with the overall tree’s health as the primary focus.
Topping, “hat racking” or “rounding-over” a tree can put a tremendous amount of stress on a tree. The practice can result in the removal of 50-100% of the tree’s leaves. This extreme reduction in a tree’s leaf bearing canopy places tremendous stress on the tree. If the tree doesn’t die it will use a large portion of it’s starch reserves (stored in the roots) to replace the removed canopy. The replacement shoots will grow quickly from buds located in the outer tissue around the removed branches, but will not be anchored the same as a “normal” branch. This poor attachment point and fast growth often results in these “shoots” failing.
Residential tree improperly trimmed called “topping” (click to enlarge)
The large wounds left after a tree has been topped expose the tree to more hazards than just fast growing, poorly attached shoots. The wounds are slow to heal (if they heal at all) and the exposed cambium layer is vulnerable to insects, disease, and decay. The remaining portion of the tree can also experience sunburn or “scalding” due to the lack of leaves and sun exposure.
After explaining this to a potential client I am often asked “then what should I do?” Depending on the species, location, health and client desires there are several options. Proper reduction pruning is one solution and involves reducing limbs according to industry standards (Click here to see our pruning guide). If the tree is in poor health or an unfortunate location, removal is also an option. Often times it is better to remove a poor specimen and replace it with a species that is better suited to that particular site.
As we learn more about the value of trees in our urban forest we have a responsibility to be good stewards of our trees. Witnessing the proverbial “light bulb” turn on after discussing the practice of topping trees is one of the many rewards of being an arborist.
Sincerely,
Chris Gill
Regional Manager, Russell Tree Experts
ISA Certified Arborist® OH-6416A