What is topping?
Topping is the drastic removal or cutting back of large branches in mature trees.
The tree is pruned much as a hedge is sheared and the main branches are cut to stubs.
Topping is also referred to as heading, stubbing or dehorning.
Why are trees topped?
Many homeowners have their trees topped often by so-called professionals when their trees have reached heights which they consider unsafe.
They fear a strong wind might blow these large trees over.
This fear is largely unjustified. The extensive root system of a healthy tree, if left relatively undisturbed, provides adequate support for the tree.
An old healthy tree with a good root system is actually less likely to blow over than a smaller tree with its smaller, less developed root system.
Some homeowners believe that the stimulation of new growth associated with topping is actually beneficial to the tree.
Although the tree appears rejuvenated with new foliage and branches, this only serves to mask the real damage topping does to the tree.
Trees may also be topped to remove potentially hazardous and diseased branches which may break off in ice or wind storms.
Unfortunately, topping removes both healthy as well as unhealthy limbs.
The hazardous limbs are best removed by selective pruning instead of topping.
Large, mature trees are often topped to prevent interference with overhead utility wires. They are also topped when they block views, interfere with buildings or other trees, or when they shade solar collectors or other areas — such as lawns and gardens where sunlight is wanted.
In some of these situations, removing large limbs may be necessary.
However, correct pruning alternatives such as proper early training, selective thinning out of branches and limbs, or whole tree removal should be considered and adopted where feasible.
Why is topping damaging to trees?
Topping can damage a tree in the following ways:
— Removing much of the tree canopy upsets the crown-to-root ratio and seriously affects the tree’s food supply.
— Removing the tree’s normal canopy suddenly exposes the bark to the sun’s direct ray, often scalding the newly exposed outer bark.
— Topping removes all the existing buds which would ordinarily produce normal sturdy branches.
— Large branch stubs left from topping seldom close or callus. Nutrients are no longer transported to the large stubs and that part of the tree becomes unable to seal off the injury.
— Topping stimulates the regrowth of dense, upright branches just below the pruning cut.
These new shoots, referred to as suckers or water sprouts, are not as structurally sound as are the naturally occurring branches.
— Without resulting foliage, a bare trunk results and the tree quickly dies.
— Deteriorating branch stubs are highly vulnerable to wind and ice damage.
— From an aesthetic aspect, topping disfigures the tree.