What Is an ISA Certified Arborist?

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International Society of Arboriculture Certified Arborists diagnose tree problems (diseases, insect infestations, and decline), implement strategies to mitigate poor tree health, and provide emergency tree care.


What does it mean to be an ‘ISA Certified Arborist’? It means the arborist has been through a rigorous training and testing process to assure that he or she meets the standards set by the International Society of Arboriculture for a qualified professional arborist. These persons are well trained in tree health, pest management, soil fertility, assessing storm damage, cabling and bracing, and proper pruning techniques. In other words, they are specialists in the care of trees.

When an arborist does a tree health consultation, he or she evaluates tree health and tries to recommend a plan to stop any tree decline. The arborist might recommend pruning to remove any dead wood or to shape the tree. If the tree has any unsafe branches or bad branch angles, the tree professional might cable the offending limbs. Cabling involves using heavy gauge stainless steel cable and eye bolts to secure limbs and trunks. The arborist may recommend a fertilization regime to increase the tree’s vigor and stop any decline. Trees are often fertilized using a liquid fertilizer injected into the soil around the tree.

tree climberIf the tree is not salvageable, then the arborist will recommend removing the unhealthy tree. Often, the tree will be in a location where it cannot be felled easily. Maybe there is a structure under or near the tree or the tree is near the property line. In this case, the arborist may decide to rope the tree. Climbing the tree, the arborist ties ropes to the branches. Then the branches are cut off one by one allowing the rope to break the fall. In essence the tree is removed from the top down.

The branches will be lowered down gently to workers on the ground to prevent any unwarranted damage. After removal, the company will chip the tree into mulch with a machine or haul it away. Reputable companies will leave the property only after they have cleaned up the mess and the customer is satisfied.

Tree work is tough and physically demanding. Imagine spending your whole day southern red oak sunriseclimbing towering trees with spikes on your boots and a chainsaw attached to your belt. Arborists are always wearing safety rigging that is attached to the main trunk of the tree. The rigging is the same type used by mountain climbers. Every responsible tree person wears safety rigging, a hard hat, earplugs, and eye protection.

Trees are assets that add value to one’s property and should be cared for properly. With the help of ISA Certified Arborists, homeowner’s trees will remain healthy and safe through proper fertility management and pruning. You can find an ISA Certified Arborist here. When soliciting for quotes for tree care work, ask for proof of liability and Workers Compensation insurance and references as well. Always get three estimates. You will usually be required to sign a contract, so read it carefully.

Written By

Steve Pettis, N.C. Cooperative ExtensionSteve Pettis, Jr.Extension Agent, Agriculture - Consumer and Commercial Horticulture Call Steve E-mail Steve N.C. Cooperative Extension, Henderson County Center
Posted on Apr 8, 2021
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