Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
6/14/99
Contacts:
Mark Vitosh, Forestry Extension, (515) 294-6739, mvitosh@iastate.edu
Elaine Edwards, Extension Communication Systems, (515)
294-5168, eedwards@iastate.edu
Yard and Garden Column for the Week Beginning June 18
Dehorning Trees Is Not In Style
By Mark Vitosh
Extension Forestry Specialist
Iowa State University Extension
Dehorning trees? This sounds like something out of an old western movie, but it is actually a method of branch removal that is very damaging to trees. Other names used for dehorning include topping, stubbing, heading back and rounding off. Dehorning, is basically the removal of the entire top of a tree, with the final appearance of the tree looking like a large stubby coat rack. Often when a tree is damaged by a storm, is unhealthy or when the landowner thinks the tree is growing too large, dehorning or topping is used. This form of branch removal is not recommended because it weakens a tree, reduces the tree's ability to produce food, creates a potential hazardous situation and makes the tree look pretty ugly.
When live branches are removed an open wound is created. Normally, if branches are removed properly the tree uses its natural defense system called "compartmentalization" to seal-off the wound and reduce the introduction of decay into the wood. When trees are dehorned, this natural defense system of the tree is compromised and the large improperly pruned stubs are open entry locations for decay-causing organisms and insect attack. These types of problems can greatly reduce the useful life-span of a tree.
A major misunderstanding related to dehorning is that it can rejuvenate an unhealthy tree. Instead of improving tree health, this method of branch removal puts a tree under tremendous stress. A tree needs foliage to manufacture food, and when a tree is dehorned, 70 to 90 percent of the living crown (branches and foliage) is removed. Without a living crown, a tree is forced to use valuable food reserves, which stresses a tree and increases the potential of health problems.
Since a large percentage of the living crown is removed during dehorning, the tree responds by releasing large amounts of new succulent sprouts. The tree responds this way because the tree needs to manufacture food again before it starves. The problem with these new sprouts is that they are weakly attached to the sides of the large open stubs left by dehorning. As these sprouts increase in size, they become susceptible to breakage during ice and wind storms, creating a potential hazardous situation if the tree is near a target (e.g. house, sidewalk or street).
If it isn't bad enough that dehorning can potentially shorten the life of a tree, make it more susceptible to decay and insect problems, and more susceptible to breakage during storms, it also makes a tree look ugly. This form of branch removal destroys the natural beauty and structure of the tree, unless you really like looking at a 30-foot disfigured pitchfork-looking tree in your yard.
Instead of just stubbing branches anywhere during pruning, remove them back to another dominating branch or to a location on the trunk called the branch collar. This proper type of branch removal promotes the tree's natural response to wounding, and allows the tree to seal-off the pruning wounds. More information on proper pruning can be found in ISU Extension pamphlet SUL-5, "Pruning Trees and Shrubs," which is available at your county extension office.
When dealing with larger trees it is recommended that you contact a professional arborist (tree service) for assistance. There are qualified arborists throughout the state, but as with any other type of business, there are always a few individuals that may not have the client's best interest in mind. When hiring individuals or companies for tree care services consider the following:
1) Beware of people knocking on your door offering to work on your tree. Most established arborists do not create new business by going door-to-door. Also, do not hire someone that tells you dehorning or topping is the best thing for your tree.
2) Make sure the arborist has a license to work in your community, if one is required (check at city hall).
3) Check with friends or neighbors who have had work done by a reputable company or individual. Check local references.
4) Make sure the individual or company has insurance for personal and property damage, and workers compensation. Ask for evidence of this insurance.
5) If time permits, obtain tree work estimates from several arborists. Make sure to get a written estimate listing all work to be done. The cost of good tree care is not cheap. Most arborists have a heavy investment in equipment, labor, safety training and insurance; a bid for a job has to reflect many of those costs.
6) Don't pay for the job until everything agreed upon is completed.
ml: isugarden
Extension programs are available to all without regard to race, color, national origin, religion, sex, age, or disability.