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Archive for Thursday, February 22, 2007

Tree topping adds, rather than reduces, hazards

February 22, 2007

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Regular readers of this column know that it is not my style to preach or chastise individual gardening practices.

However, after spending the long weekend traveling in the spacious luxury of Amtrak's Missouri Mule to St. Louis and back, I feel compelled to climb atop my soap box and begin a lecture on the perils of tree topping. Rural homesteads, small town main streets, major metropolitan subdivisions are all in the shadows (or lack thereof) of mature trees that have been topped or stripped of all but the major scaffold branches. Here is what you need to know about tree topping and why it is a practice that should never be allowed in your landscape.

According to the International Society of Arboriculture, topping is perhaps the most harmful tree pruning practice known. This and much of the following information comes from an informational brochure titled: "Why Topping Hurts" from www.isa-arbor.com.

Topping is the removal of the lateral branches from a mature tree. All that is left standing are the trunk and major scaffold branches. The most common reason given for topping is to reduce the size of the tree.

Many homeowners fear that the mature tree is too large for the property and poses a hazard. The logical cure is to reduce the size of the tree. Not true. The fact is, topping will make a hazardous tree even more dangerous.

Topping stresses the tree. When the lateral branches are removed, the leaves, or "food factory" of the tree, are removed, too. The tree must grow new branches to produce new leaves as quickly as possible. If the tree is weak or does not have enough reserve energy to do so, then it will slowly start to die. Likewise, open wounds are prone to wood decay and fungus, and harmful insects are attracted to the chemicals given off during the healing process.

Topping creates hazardous growth. Every pruning cut results in the growth of dozens of dormant lateral buds. These shoots can grow as much as 20 feet in one season. Combine that with the fact that they are not firmly attached, these limbs become even a bigger hazard than the original branches once they mature.

Finally, topping can lead to sunburn. Thousands of leaves provide shade for the limbs and trunk - blocking the sun's rays and absorbing the intense heat. Once removed, the trunk and limbs are exposed to these harsh conditions leading to bark splitting, cankers, scorching of the delicate vascular tissue and branch death.

In a nutshell, topping is neither a recommended nor accepted practice in tree care. There are, however, several safe alternatives. Next week I will climb down from my box and explain the pros and cons of selective branch removal and tree replacement.

- Bruce Chladny is horticulture agent at K-State Research and Extension-Douglas County. For more information, call him at 843-7058 from 8 a.m. to 5 p.m. weekdays.

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