Topping A Tree: Why You Should Think Twice

Topping a tree, which involves cutting off the top portion of the tree to reduce its height, is considered bad practice for several reasons, particularly because it can harm the tree's health and structure.

Disrupting Natural Growth: Trees have a natural growth pattern, with the main leader (top stem) guiding the tree's upward and outward growth. Topping removes this leader, leading to the growth of multiple, weaker shoots that sprout from the cut area. These shoots often lack the strength and structure of the original leader, which can result in a weaker tree overall.

Stress and Vulnerability to Disease: The large cuts created by topping expose the tree to infection and disease. Trees naturally seal off wounds through a process called compartmentalization, but the size of the cut from topping often exceeds the tree's ability to seal it properly, leaving the tree more vulnerable to pests and pathogens.

Altered Water Uptake: Topping also alters the tree's ability to take up water. The leaves of a tree are responsible for transpiration, which creates a vacuum effect that helps pull water up from the roots. By removing the top branches, you reduce the amount of leaf surface area available for this process, which can disrupt water flow and nutrient transport. As a result, the tree may experience dehydration, nutrient deficiencies, and reduced overall health.

Decay of New Growth: The new shoots that grow after topping are often poorly structured and may grow too quickly, leading to weak wood that is more prone to breakage. Additionally, the rapid regrowth often places a strain on the tree's resources, leading to poor maintenance of its water and nutrient supply.

Structural Weakness: Topping can also lead to poorly balanced growth, with the tree becoming top-heavy or lopsided as new shoots grow unevenly. This can cause a higher risk of limb breakage during storms or high winds, further stressing the tree.

For all these reasons, arborists generally recommend alternatives to topping, such as selective pruning, which preserves the tree's natural growth pattern while addressing the specific needs of the tree or landscape.