An arborist is a specialist in the care of individual trees. Arborists are knowledgeable about the needs of trees, and are trained and equipped to provide proper care. Hiring an arborist is a decision that should not be taken lightly. Proper tree care is an investment which can lead to substantial returns. Well-cared-for trees are attractive and can add considerable value to your property. Poorly maintained trees can be a significant liability. Pruning or removing trees, especially large trees, can be dangerous work. Tree work should only be done by those trained and equipped to work safely in trees. Certified Arborist List

Services That Arborists Can Provide

Arborists can provide a variety of services to help maintain your valuable investment.
  1. Pruning---The arborist can determine what type of pruning is necessary to maintain or improve the health, appearance and safety of your trees. These techniques include:
    • Eliminating branches that rub each other.
    • Removing limbs that interfere with wires, building facades, gutters, roofs, chimneys, or windows, or that obstruct streets or sidewalks.
    • Removing dead or weak limbs that pose a hazard or may lead to decay.
    • Removing diseased or insect-infested limbs.
    • Creating better structure to lessen wind resistance and reduce the potential for storm damage.
    • Training young trees.
    • Removing limbs damaged by adverse weather conditions.
    • Thinning or removal of unnecessary branches.
    • Improving the shape or silhouette of the tree.
  2. Removal---Although tree removal is a last resort, there are circumstances when it is necessary. An arborist can help decide whether or not a tree should be removed. Arborists have the skills and equipment to safely and efficiently remove trees. Removal is recommended when:
    • The tree is dead or dying.
    • The tree is considered irreparably hazardous.
    • The tree is causing an obstruction that is impossible to correct through pruning.
    • The tree is crowding and causing harm to other trees.
    • The tree is to be replaced by a more suitable specimen.
    • The tree should be removed to allow for new construction.
  3. Emergency Tree Care---Storms may cause limbs or entire trees to fail, often landing on homes, cars, other structures or other trees. The weight of storm-damaged trees is great and they can be very dangerous to remove or trim. An arborist can assist in performing the job in a safe manner, while reducing further risk of damage to your property.
  4. Planting---Some arborists plant trees and most can recommend what types of trees are appropriate for a specific location. The wrong tree in the wrong location could lead to future problems due to limited growing space, insects, diseases, or poor growth.
  5. Other Services---Many arborists also provide a variety of other tree care services including:
    • Practicing Plant Health Care, a concept of preventive maintenance to keep trees in good health, which will help the tree better defend itself against insects, disease and site problems.
    • Fertilization.
    • Cabling or bracing for added support to branches with weak attachment.
    • Aeration to improve root growth.
    • Installation of lightning protection systems.
    • Spraying or injecting to control certain insect and disease problems.

Selecting the Right Arborist for the Job

There are a variety of things to consider when selecting an arborist which include:

What Is a Certified Arborist?

An arborist by definition is an individual who is trained in the art and science of planting, caring for and maintaining individual trees. ISA Arborist Certification is a non-governmental, voluntary process by which individuals can document their base of knowledge. It operates without mandate of law and is an internal, self-regulating device administered by the International Society of Arboriculture. Certification provides a measurable assessment of an individual's knowledge and competence required to provide proper tree care.
Certification is not a measure of standards of practice. Certification can attest to the tree knowledge of an individual, but cannot guarantee or ensure quality performance.

Certified arborists are individuals who have achieved a level of knowledge in the art and science of tree care through at least three years experience and who have passed a comprehensive examination developed by some of the nation's leading experts on tree care.

Certified arborists must also continue their education to maintain their certification. Therefore, they should be up-to-date on the latest techniques in arboriculture.

Be an Informed Consumer

One of the best methods to use in choosing an arborist is to educate yourself on some of the basic principles of tree care. ISA offers several other brochures in this series which discuss many of the basic principles of tree care.
Why Hire an Arborist
Benefits of Trees
Buying High-Quality Trees
Insect and Disease Problems
Mature Tree Care
New Tree Planting
Tree Selection
Plant Health Care
Recognizing Tree Hazards
Trees and Turf
Avoiding Tree & Utility Conflicts
Tree Values
Why Topping Hurts Trees
Pruning Young Trees
Pruning Mature Trees
Avoiding Tree Damage During Construction
Treatment of Trees Damaged by Construction

Your local garden center, county extension agent or city arborist are also excellent sources of information if you should have further questions. They may also be able to refer you to certified arborists.

This brochure is one in a series published by the International Society of Arboriculture as part of its Consumer Information Program. You may have additional interest in the following titles currently in the series: Insect and Disease Problems; Mature Tree Care; New Tree Planting; Trees and Turf; Benefits of Trees; Tree Selection; Plant Health Care; Avoiding Tree and Utility Conflicts; Recognizing Tree Hazards; Why Hire an Arborist; Buying High-Quality Trees; Tree Values; Pruning Young Trees; Pruning Mature Trees; Why Topping Hurts Trees; Pruning Young Trees; Pruning Mature Trees; Avoiding Tree Damage During Construction; Treatment of Trees Damaged by Construction.

Developed by the International Society of Arboriculture (ISA), a non-profit organization supporting tree care research around the world and dedicated to the care and preservation of shade and ornamental trees. For further information, contact: ISA, P.O. Box 3129, Champaign, IL 61826-3129, USA.

1995 International Society of Arboriculture.