Reasons Tree Topping is Discouraged
Tree Topping is the practice of severely cutting limbs larger than 3 inches in diameter to stubs within the tree’s crown so as to remove the normal canopy and disfigure the tree.
Reasons Not to Top Trees
The following information comes from the North Carolina Urban Forest Council.
A tree’s crown is like an umbrella that shields much of the tree from the direct rays of the sun. By suddenly removing the protection, the remaining bark tissue is so exposed that scalding may result. It can also be a dramatic effect on neighboring trees and shrubs. If understory vegetation thrives in shade and the shade is removed, poor health and death may result.
Good pruning practices rarely remove more than half to one-third of the crown, which in turn does not seriously interfere with the ability of the tree’s leafy crown to manufacture food. Topping removes so much of the crown that it upsets an older tree’s well-developed crown-to-root ratio and temporarily cuts off its food-making ability.
A topped tree is a disfigured tree. Even with its regrowth it never regains the grace and character of its species. The landscape and the community are robbed of a valuable asset, and property value declines.
Rapid New Growth
The goal of topping is usually to control the height and spread of a tree. Actually, it has just the opposite effect. The resulting sprouts (often called water spouts) are far more numerous than normal new growth and they elongate so rapidly that the tree returns to its original height in a very short time – and with a far denser crown. This created the need for a lot more routine tree maintenance than an untopped tree and at a far greater cost.
Insects & Disease
The large stubs of a topped tree have a difficult time forming callus. The terminal location of these cuts, as well as their large diameter, prevent the tree’s natural defense system from doing its job. The stubs are highly vulnerable to insect invasion and spores of decay fungi. If decay is already present in the limb, opening the limb will speed the spread of disease.