“Topping” a tree — that is, removing 50 to 100 percent of the tree’s canopy or top, is extremely damaging, causing weak branching and in some cases the death of a tree, say Bismarck city arborists.

The city arborists say they have observed “topping” of trees in the community and want people to be aware of its hazards.

With at least 50 percent of the canopy being pruned out, the tree will rapidly produce shoots right below the pruned section to compensate for the lost leaves. Since these shoots are formed quickly and profusely, the attachment is not strong.

The wound left from topping can become a hazard of its own because of potential decay and rot issues. Since so many large stubs are left behind from topping, the tree is not likely able to callus over all of the open wounds. These wounds leave an open path for insects, diseases, and decay to form in the tree. Branch failure is prone to happen due to the added weight from the shoots growing off of a weakening branch stub.

The bark of a topped tree can also be affected. When 50 percent or more of the leaves are lost during topping, trees can actually get sunburned due to the loss of shade. This damages the inner tissues of the tree causing the bark to split and cankers to form. These cankers ultimately destroy a tree by causing loss of structural integrity.

The city of Bismarck Forestry Department maintains a list of licensed arborists that it encourages citizens to use for tree trimming. For a list, visit www.bismarck.org/forestry and click on Pruning and Licensed Commercial Arborists. For other information, call 355-1733.