Don't Destroy Your Large Trees by Topping

Curtis E. Swift, Ph.D., Area Extension Agent (Horticulture) Colorado State University Extension

tree destroyed by improper pruning

Photo by Ralph Selch, CSU Continuing Master Gardener

Topping

The process known as topping is the indiscriminate removal of a tree's crown, cutting off large branches and the main stem of the tree, leaving large branch stubs. These stubs often die back, are vulnerable to decay and result in a profusion of unsightly and weakly attached adventitious branches. Topping also may result in the sunscald of the upper branches due to the sudden removal of the leaves and branches above.

Pollarding is an extreme type of pruning similar to topping that is done in some parts of the world. With pollarding all the new growth is removed annually.

Results of Topping

Dead stubs and internal rot due to improper pruning

This photograph shows the dead stubs resulting after topping the tree. Also seen are weakly attached branches that originated from adventitious buds near the pruning cut.

The reason for this improper method of pruning is often based on the mistaken fear that tall trees will fall on homes and other buildings during storms. In some areas of the country `topping' is such a common procedure that it appears the correct method of pruning. In fruit growing areas, where orchard trees are topped on a yearly basis to keep them at a height for the easy harvest of fruit, area residents often mistakenly believe this same technique should be used on ornamental trees as well. This belief is strengthened by `arborists' who either know no better practice or find topping the easiest and most profitable method to use.

Large, sound limbs are not dangerous in unseasonable snowstorms or windstorms. Large limbs become unsafe when decay enters as a result of past pruning neglect or improper pruning as results with topping.

One of the worst examples of topping I have ever seen

topping trees leaves dead stubs

And to make things worse, the neighbor hired the same tree 'butcher'.

topping a tree

Or, they decided to prune the trees themselves!

Internal Rot

Internal rot due to topping

Tree topping results in the development of internal rot on many trees. The cylinder of rot that develops in the tree is often the same diameter as the main stem that was removed. In other words, a main stem that is twelve inches in diameter at the time it was cut can lead to a twelve inch diameter of rot that extend for many feet inside the trunk of the tree. Such internal rot creates a tree that may become a hazard in later years.

The branches that develop around the stubs left from improper pruning develop from latent buds that are buried deep beneath the bark. These new branches give the tree the appearance of a porcupine. This new succulent growth is not properly attached to the tree and very susceptible to wind breakage.

Placed on the Internet May 21, 1996; updated Decembr 23, 2009