Also, a correct cut results in more rapid wound closure by callus tissue so that the bark's continuity is eventually re-established. Branch stubs produced by topping harbor decay fungi which eventually break down the barrier in the collar and then proceed into the trunk. Whenever a cut is made in the main leader by topping, there is nothing to prevent decay from developing in the trunk. The tree may be structurally weakened and its useful life span reduced. Once-shaded bark in the canopy becomes scalded by exposure to direct sunlight.
Stubs are likely to attract wood-boring insects.
Stubbing stimulates the development of watersprouts just below the cut. These shoots grow rapidly, causing a topped tree to grow back to its original height faster and denser than a properly pruned tree. The watersprouts are also weakly attached and are easily broken off in storms. If the height of a tree has to be reduced because of storm damage or interference with electrical wires, it can be correctly done by a method called crown reduction or drop crotch pruning. The procedure involves the removal of a main leader or main branch at the point of attachment of a lateral branch.