Topping Hurts!

Douglas L. Airhart & Guy Zimmerman III

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Topping Hurts- General Information:

(Figure 8-1) Topping Trees Hurts!

Why not top trees?

Video Vignette (See it live!)

From Tree City USA Bulletin No. 8, 1989, Used with permission of The National Arbor Day Foundation.

Iles (1989, p.51) described topping as “the drastic removal of large branches with little regard for location of the pruning cuts”. Although topping trees is a common practice in many communities, it is NOT a professional method for pruning trees. It is not a practice that should be performed by any certified arborist because there are professional pruning techniques to limit the height of a tree.

(Figure 8-2) Proper Height Reduction of a Mature Tree.

Topping practices do not follow the rules of pruning that protect the branch collars or that stipulate size limits for pruning to lateral branches, thus they are not made in a professional manner and leave stubs of branches in the canopy. These stubs are not protected from decay organisms, and open the tree to invasion by insects and decay. This decay can penetrate to the lower branches and trunk of the tree and cause its rapid decline and possibly death. These problems are shown in Figure 7-3.

Topping, or “rounding over” is mistakenly believed to control the height of a tree. However, the new stems will soon grow to be the same height as the tree is genetically programmed to be. But the new stems will be numerous and crowded and weakly attached at the point of topping. Many of these will die back and fall off during windy weather.

(Figure 8-3) Tree Topping Example.

Two tree topping events are visible in this picture. The limbs grew from stubs of three branches, and the new limbs are crowded.

The lower left branch shows the weakened precarious attachment of the new limb. The large fresh wound shows the size of the stub branch.

The lower right branch shows the cavity that developed in the original stub, weakening the entire tree.

Results of Improper Tree Topping: Limb Dissection Example - Video Vignette (See it live!)

Eight Good Reasons (NADF, 1989) to NOT "Top" :

	Starvation: topping removes so much of the crown that it upsets the crown-to-root ratio and limits the food-making ability of the tree.
	Shock: the canopy of leaves casts shade on the internal branches. Topping removes the shade and exposes the internal bark to sun scald.
	Pests and Disease: topped branches have large wounds that cannot seal nor defend the wound from insects and decay.
	Weak Limbs: new sprouts develop at the edges of the cut branches, and are weakly attached. If the stub rots, the sprouts will break even sooner.
	Rapid New Growth: height control by topping is doomed to fail. The new branches grow fast and furiously to the original height, but much more crowded.
	Tree Death: some species, e.g. beech, do not tolerate topping and the reduced foliage may cause the tree to die.
	Ugliness: topped trees are so disfigured that they will never recover their original grace.
	Cost: topping can be done quickly because good decisions about pruning are not needed. But trees that die will need replacement, the ugly trees reduce property values, the dead stubs become liabilities, and more maintenance will be needed.

Pollarding:

There is a pruning technique that looks like topping, called pollarding (Harris, 1999). It works only on certain trees, and it requires frequent and consistent pruning. Pollarding consists of cutting back branches to a selected point of fixed height, but continuing to cut the branches every year or every other year to create a compact canopy.

Gilman (2002) compares differences between topping and pollarding.

Topping:

	Common, but inappropriate;
	Stem diameter and age not considered;
	Practiced on any trees of any age;
	Return pruning may not happen;
	Causes decay in cut branches;
	Creates weak attachments that may become dangerous;
	Can decrease the tree life span.

Pollarding:

	Rare, but appropriate technique;
	Begins when tree is young;
	Applied every one or two or three years;
	All shoots are removed each time;
	Shoots are only 1-inch diameter when removed;
	Does not cause trunk decay;
	Creates good structure;
	Can have extended life span.

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TLCforTrees.info is maintained by: Douglas Airhart, Ph.D. Certified Arborist & Jeff Plant, Ph.D, Last Updated on: 07/11/03