Topped branches respond with a vigorous growth of weakly attached limbs that are more susceptible to breakage and storm damage and require more frequent maintenance than the original branches. Trees are usually topped by well-intended, misinformed people. Contrary to the many myths in its defense, topping is the worst thing you can do for the health of your tree.
After a tree is topped, decay and sun scald damage and destroy once healthy tissue, and the significantly reduced canopy cannot produce enough food to maintain healthy functioning. Disease and insect pests take advantage of the tree’s increased vulnerability and can weaken the whole tree down to the roots. Topping leads to immediate death in some species and reduced lifespan in others.
Topping publicly-owned trees, including trees in the right-of-way between the sidewalk and the curb, can lead to fines and/or mandatory removal and replanting of the topped tree.