That is what can happen if you hire and untrained, inexperienced person to prune your trees. There are many people who fancy themselves arborists, but that's a term reserved for persons who have the expertise and are qualified to improve the quality of your tree through selective pruning, not destroy it with random hacking! 

Before selecting a specific person or company to prune your valuable trees, ask some important questions to help select the most qualified to do the job. 

Ask for a brief description of the arborist's formal training and practical experience. A professional arborist will be proud of his background. While formal education courses are not always necessary, a definite display of ongoing local and regional continuing educational courses is strong evidence of a progressive attitude and a desire for professional enhancement.

Certification is another indication of competency. A certified arborist is an individual who has achieved a level of knowledge in the art and science of tree care through at least three years experience and having passed a comprehensive examination. Certification is administered by the International Society of Arboriculture and the National Arborist Association. 

Know what specific services the person or company performs. In addition to tree pruning, most professionals also provide fertilization, pest control, and careful inspection services. If pruning or removal is to be done, make sure adequate cleanup services are provided.

Find out how long will the work take. The professional arborist will be able to accurately estimate the length of time the job will take, and then stick to it.

Make sure the person or company your considering has proof of liability and workmen's compensation insurance, and an occupational license. Require proof be shown prior to entering into a contract for services. Be sure to check the effective dates for such coverage.

As I mentioned earlier, a certified arborist is a person with proven knowledge about trees. If your considering an non certified arborist, ask some questions to determine their level of knowledge.

Ask if pruning paint will be used to treat wounds. If the answer is "yes", the person or company is not up to date with recommended procedures. Pruning paint provides no specific benefits. In fact, the use of pruning paint to dress wounds can inhibit the natural healing process of the tree.

Ask the arborist to identify several of your trees. Any competent arborist should be able to properly identify (by common and botanical name) most of the trees that grow here. If there is a hesitancy to perform this simple task, or if the responses contain major errors, then you have a non-professional.

Question the arborists experience in basic pruning techniques. Answers should indicate a strong reluctance to "top" trees. The arborist should be able to explain to you what "target pruning", "flush cuts", "drop crotch pruning", thinning, and "dead wooding" are. Don't hesitate to ask for a graphic demonstration on you own tree. The arborist may show you by pointing or actually making a cut.

Ask for three or more local client references, with phone numbers and the approximate time the tree work was performed. Any hesitancy to provide this information should serve as a red flag!

If the tree is recommended for removal, are you given other options? What are the options? Many instances occur when a tree does not have to be removed in order to improve a situation. Root pruning, proper branch pruning, changing grass lawn to ground cover or mulch, etc.

Ask for a complete estimate of all services recommended before signing a contract. This should be on a formal estimate sheet with complete details of all work intended to be performed. In addition, there should be a work guarantee in writing which assures you adequate protection. Read it carefully before signing any document.

Finally, ask for a formal contract. For you protection against possible future disagreement over what services were suggested and agreed to, this is a valuable document. If you sign, be sure receive a legible copy for your files.

Written by John Begeman, College of Agriculture and Life Sciences, the University of Arizona, 520-626-5161.
Material originally appeared in Arizona Daily Star gardening column, on April 5, 1998
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