Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: SUNDAY, January 3, 1993 TAG: 9301040361
SECTION: HOMES PAGE: D-1 EDITION: METRO
SOURCE: John Arbogast
DATELINE: LENGTH: Medium
POOR PRUNING CAN BE HAZARDOUS TO A TREE'S HEALTH
Q: A 50-foot maple tree grows 14 feet away from my home. It branches off in four directions three feet from the base. Tree experts have advised me that it should not be pruned because that process would cause sucker growth and make my tree weaker. Please advise; can this tree be topped (15 to 20 feet) or should it be secured with cables? I do want to keep my tree. J.T., RoanokeA: Your letter brings a lot of tree information to mind that I am going to pass along to readers.
It is difficult to give the best recommendations in a situation like yours without seeing the tree and the site. I can say that it would be very unwise to have a major portion of any healthy tree removed at one time. The word "topping" should not be in good tree-care vocabulary. I'm assuming that you used that word in the usual sense, which refers to the severe cutting back of branches with very little regard for the shape of the tree.
Since you said that you want to keep your tree, I would suggest that having the tree cabled and braced by a trained arborist would be the best option. Of course, I would ask the question "is the tree worth saving?" A maple that separates into four trunks would be a prime candidate for splitting, which hopefully proper cabling and bracing will prevent.
I must admit that I don't know of any guarantee an arborist gives when strengthening such a tree. Also, because your maple is only 14 feet from your house, I would wonder about roots possibly damaging your foundation or basement. In other words, it might be more economical to remove the maple and replace it either with another shade tree you can train into a strong shape farther away from the house, or a small tree like a dogwood in the same spot.
The tree experts you talked to must have been thinking about removing a considerable amount of growth since they cautioned you that it would lead to sucker growth and a weak tree. That will happen.
Drastic trimming of a tree may seriously affect its food supply. With less leaf area during the next growing season, a tree will produce and store less food. This puts the tree in a stressful situation and makes it more susceptible to insect damage and injury due to cold, drought and disease. The older a tree when it is topped, the less tolerant it is of severe pruning.
Proper tree pruning should not leave large wounds or stubs as topping does (a stub is the branch portion left when a pruning cut is made between existing leaves, buds, or side branches rather than just outside one of those parts). Large stubs that are larger than 3 inches in diameter seldom heal completely. Branch decay and premature death of shade trees often can be traced to large wounds left from improper pruning. Topped branches can't form a natural healing layer known as a callus layer.
Improper pruning, especially drastic removal of living parts, can injure a tree and even shorten its life. According to James E. Johnson, associate professor of forestry at Virginia Tech, it can take up to 20 years for a topped tree to die.
Pruning your maple will cause sucker growth because topping or cutting a tree back stimulates dense shoots to grow from the cut branch stub. Those dense new twigs are brittle and likely to break easily in high winds. Also, because the proliferation of new growth behind those big cuts may be crowded, there will be reduced air flow through the tree, which again can lead to an ideal breeding ground for insects and diseases.
A better pruning practice for an established shade tree would be to make thinning cuts, which does not stimulate new shoots. That means completely removing limbs back to the branch collar at the major side branch or trunk from which the limbs grow. Thinning lets more air and light into the inner portions of a tree and reduces the tree's wind resistance.
READERS: this column is more interesting when you write. So, got a question about your plants, lawn, garden, or insects? Write to Dear John, c/o the Roanoke Times & World-News, P.O. Box 2491, Roanoke
Gardener's checklist
Keep your Christmas poinsettia and other holiday flowering plants looking great by placing them in a location of bright light, no drafts, 60 to 70 degrees; and complete watering only when the soil feels just slightly damp to the touch. Remember that these flowering plants are living things, and not just decorations.
John Arbogast is the agriculture extension agent for Roanoke