Proper Techniques for Pruning Branches on Trees

February 7, 2011 at 4:25 pm Leave a comment

When it comes to pruning trees there can be several different theories and practices out in the real world. The purpose of this article is cover one small aspect of tree pruning, the pruning of limbs and branches.

Before any pruning takes place there is one question that everyone needs to ask, why prune? The reason for pruning is to promote the health of the tree and to train the tree to grow properly. “Pruning is a double-edged sword, either helping or hurting according to if, where, when, how, and why it is applied. When properly executed, a variety of benefits can occur. Benefits include reducing risk of branch and stem breakage, better clearance for vehicles and pedestrians, improved health and appearance, enhanced view, …… When improperly performed, pruning can harm the tree’s health, stability, and appearance.”

In order to make a proper pruning cut, a little basic tree biology is need. Here is what we need to know before any pruning cut is made;

1. Identify the Branch Bark Collar
2. Branch defense zone cells
3. Branch Bark Ridge

When we understand these three terms, we will be able to make a proper pruning cut.

The identification of the Branch Bark Collar is the most critical aspect of our pruning cuts. Where the branch meets the limb or trunk there is a swollen area at the base of the branch. In the photograph above, you will see, the branch bark ridge (arrow), the place to make the correct cut (marked by the dark line), and the branch bark collar between the two. The pruning cut made, as indicated by the dark line, will be a healthy cut.

In the photographs to the left you can see the results of improper pruning cuts. The cuts on these two trees show evidence of decay, the inability of the tree to form wound wood and the onset of cankers. These cuts may cause the death of the tree.

When a cut is made flush to the trunk or branch, the wound eliminates the trees’ natural ability to seal over the wound. In the branch bark collar there is a natural branch defense zone. This zone protects the tree from the wound by initiating chemical changes that protects the trunk from decay. To cut through the branch bark collar disrupts the trees’ defense zone opening it to what you see in the photographs above.

The above article is just the tip of the iceberg when it comes to the proper care of trees. For further information on any horticultural practices I will refer you to universities throughout our country and their researched based information.

A couple of very informative sources cited in this article include:

University of Florida Pruning Shade Trees in the Landscape webiste
Colorado State University Extension Garden Notes #613: Pruning Cuts

Photograps in this article were provided courtesy of Washington State University Extension.

Jim Janks
Colorado Master Gardener, Gunnison

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Entry filed under: Trees.

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