Why Topping Hurts Trees

Topping is the most harmful tree pruning practice. Yet, despite years of literature and seminars explaining its harmful effects, topping remains a very common practice in Utah. This section will explain why topping is a horrible pruning technique. We can offer far better alternatives.

The majority of homeowners resort to topping to reduce the height of a tree, soley because the believe the tree has outgrown the property. Some feel tall trees are hazardous to their home or adjoining property. Topping, however will make a tree more susceptible to being hazardous in the long run.

You’re not saving any money by topping. After topping a tree, if the tree survives, it will require yet another pruning again within maybe one year. Pruning will be needed to keep the tree at the proper height year after year. If the tree dies it will have to be removed. Topping is an expensive way to prune a tree.

Topping often removes 50-100% of foliage from the crown of a tree. The leaves are the "food factories" and this can temporarily starve a tree. Severe pruning will trigger the survival mechanism. This forces rapid growth of multiple shoots below each cut. The tree needs to put out a new crop of leaves as soon as possible. The new shoots (often called suckers), grow very rapidly, as much as 20 feet in one year, in some species. Now remember the reason most homeowners top their trees is to reduce the height and hazardous conditions; however, now the trees are more susceptible to damage, especially in windy conditions!

Sunscald can result from topping. Leaves and branches provide thousands of leaves to absorb sunlight. If leaves are removed the branches and trunk are suddenly in direct sunlight and high levels of heat. Tissues beneath the bark may burn.

A stressed tree is more vulnerable to insects and diseases. Large, open topping cuts expose the sapwood and heartwood to be attacked. The tree may lack sufficient energy to "defend" the wounds against invasion. Some insects are actually attracted to stressed trees.

Topping can cause decay. If a tree is healthy and the wound isn't too large, the natural closing (many refer to as healing) process will occur to wound. When topping cuts are made, decay begins to move down through the branches, This can cause death of the tree.

There are alternatives to topping. There are times when a trees height or spread must be reduced. For instance, building structures, traffic, utility lines, etc. There are recommended procedures for doing this. If large branches should be removed or if a branch must be shortened, it should be cut back to a lateral that is large enough to assume the leader role. A good rule of thumb for this is to make a cut back to a lateral that is at least 1/3 the diameter of the limb being removed.