Pruning Procedures

Rainbow Treecare Arborists are trained to remove limbs on trees with the least impact to tree health. We have based much of our pruning practices on the pruning research from two scientists, Dr. Dan Neely of the Illinois Natural History Survey and Dr. Alex Shigo from the U.S. Forest Service, who both discussed wound healing as the key to successful pruning.

Researchers all agree that the “branch collar” of the limb to be pruned should not be touched. The branch collar is the region of the branch where the trunk wood and the wood from the branch intersect and join. This area of tissue connection is designed to prevent infections from coming through the branch and infecting the main trunk of the tree. If the branch collar is eliminated when pruning, the trees' natural barrier to infection and decay is effectively removed. Pruning which keeps the branch collar intact is called "Natural Target Pruning (NTP)".

When NTP is not possible, due to branch angles or other issues, we follow Dr. Neely's research that shows that cutting slightly into the branch collar does not violate the protection zone as much as leaving a stub (piece of branch sticking out of the branch collar) or cutting flush to the trunk or limb of the tree. Both stub cuts and flush cuts will cause significant decay by removing or bypassing the protection zone created by the branch collar. This form of pruning is called "Conventional Pruning".

Plant Maintenance

At times there may be situations where no branch collar exists. This is a common occurrence on linden and maple trees that exhibit co-dominance. Co-dominance is where two limbs are competing with each other for dominance and are not creating good structure. In these situations our arborists will remove up to 1/3 of one of the co-dominant limbs, back to a secondary limb. This reduction will allow the nonpruned limb to become dominate and the pruned limb to become less important or subordinate. Over a period of three years, the subordinate limb will create a branch collar to the dominant limb at which time it can be removed without removing or bypassing the protection zone of the tree. This form of pruning has been thoroughly research by Dr. Ed Gilman from the University of Florida and is referred to as "Subordination Pruning".

It is always best to have professionals prune your trees that have the knowledge and expertise to reduce wound risk and promote overall tree health*. If however, you decide to prune your own trees, please follow the diagram listed below to reduce the potential for infection of primary wood tissue**.

• Cut # 1 prevents bark and tissue tearing
• Cut # 2 removes the weight of the branch
• Cut # 3 is along the edge of the branch collar, preserving the protection zone of the tree

* Tree pruning is dangerous work. Always call a professional arborist when cutting a large limb or if the branch to be pruned necessitates the use of a ladder.
** Make sure all pruning tools are clean and free of bacteria and fungi.

An integrated approach

When caring for urban trees it is important to make a complete evaluation of all environmental conditions to accurately diagnose all stress factors and prescribe care based on specific circumstances. This prescriptive care will help your tree meet its full potential.