This practice is extremely harmful to trees. Firstly, it involves the sudden removal of a large proportion of the tree’s foliage which temporarily starves the tree of needed energy.
To compensate for the loss, the tree will promote the growth of new buds, usually from just below the stub. Homeowners may feel that this new growth represents healthy regrowth, but this is not the case. The new buds
are structurally weak and superficially anchored to the larger branch. Although very quick to grow, they can easily break in windy conditions. Thus, the original purpose of topping (pruning potentially hazardous limbs
or controlling upward growth) is defeated.
Secondly, bark that is suddenly exposed to large amounts of sunlight and heat can become scalded. This can lead to damage and often death of the limb. This again creates a potential
Thirdly, topping wounds close slowly and sometimes not at all. Insects and pathogens can therefore gain access to the tree for extended periods of time. This is a major concern if Dutch
elm disease has been spotted in the region.
Finally, topped trees are unattractive and can often contribute to a lowering of property values.