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Ruth Correll: Tree topping hurts trees

Ruth Correll • Updated Nov 8, 2017 at 3:00 PM

A homeowner recently called me because he was concerned about the health of a tree in his yard. It was immediately apparent the tree was “topped” in the past, and due to this practice, had succumbed to disease and insect damage. The practice of topping is so widespread that many people believe it is the proper way to prune trees. However, topping causes a variety of problems in trees that create future maintenance and growth dilemmas for homeowners.

Tree topping is the excessive and arbitrary removal of all parts of the tree above and beyond a certain height with no regard for the structure or growth of the tree. The vertical stem or main leader and the upper primary limbs on trees are cut back to stubs at a uniform height. Pruning on the other hand is the selective removal of certain limbs based on the structure, crown form and growth of the tree.

Topping removes too many branches and leaves which reduces photosynthesis or the food-making potential of the tree and causes depletion of the tree’s stored reserves needed for maintenance and growth. Excessive removal of crown will cause a like reduction of roots, because there is not enough leaf area or food-making capacity to sustain the amount of roots present.

Topping causes new shoots from the branch stubs, which are weak and highly susceptible to breakage from wind and ice storms or weight from excessive growth.  Another issue is the new waterspout shoots are attached to the surface of the stubs, rather than securely anchored from within the former limbs. 

Topping causes large branch wounds – those greater than 2 inches in diameter – which are slow to heal, if they heal at all, increasing the chance of insect attacks and fungal decay entering the wound and spreading throughout the tree. Bark tissues suddenly exposed to full sun may be burned, damaged, killed or develop disease cankers. Trees with thin bark such as maples, yellow poplar, flowering cherries, flowering pears and crabapples are especially susceptible to sunscald.

The natural form and structure of the crown is altered. Unsightly branch stubs, large pruning scars and undesirable, vigorous branch growth or water sprouts interfere or upset the tree’s natural beauty and form. Topping drastically shortens the life of a tree. 

Why do folks have their trees topped? Trees are often topped to reduce their size. This can be the result of poor species selection, improper tree placement or fear that a tall tree or its branches might be dangerous and fall on people or structures. This fear is one of the tree myths that lead to topping. Rarely does a healthy tree suddenly fall over or break, even in windstorms. Those trees that usually do are of advanced age, low vigor or unhealthy from mechanical injuries, insect attacks or fungal decay.

Trees are topped because they interfere with utility lines, buildings or produce too much shade for sunny areas. These conflicts may be resolved by proper species selection, better placement or correct pruning techniques. If a tree must be pruned every five years, the tree is too large for the site and should be replaced with a smaller tree. 

The remedy for topping is to “select the right tree and plant it in the right place.” If the tree is too large for the area where it happens, remove the tree and replace it with a species that is a smaller size. Avoid site obstructions both above and below ground, including utility lines. 

Topping is considered an unacceptable practice by professional organizations such as the International Society of Arboriculture and the National Arborist Association. Unfortunately, many tree services still top trees and homeowners allow them to continue. Investigate a tree service before hiring them. If a company advocates tree topping, use a different tree service. Look for membership in professional organizations. Membership does not guarantee quality, but does indicate a commitment to the profession. 

For more information, contact the UT-TSU Extension Office in Wilson County at 615-444-9584. You can also find us on Facebook or visit extension.tennessee.edu/wilson. Ruth Correll, UT Extension-TSU Cooperative Extension agent in Wilson County, may be reached at 615-444-9584 or acorrell@utk.edu.

 

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