ISA Certified Arborist Practice Exam

Tree topping involves the elimination of the upper portion of a tree, specifically cutting off the top of the tree. This practice is often intended to reduce the height of the tree or to create a certain appearance; however, it is generally considered harmful to tree health. Topping can lead to numerous issues, such as overwhelming the tree with new growth at the cut sites, leading to weak and susceptible branches. It can also expose the tree to disease and pests, as the large wounds do not heal well, and the tree ultimately struggles to survive.

This practice is clearly distinct from the other options provided. Trimming the lower branches focuses on the tree's structure and aesthetics without harming its overall health, while removing dead wood is a maintenance task aimed at promoting a tree's vitality. Applying fertilizer helps support healthy growth but does not involve physical alterations to the tree's structure itself. Thus, the specific action of cutting off the top of a tree characterizes topping correctly.