Late Winter Pruning of Deciduous Trees
By Ron Honig
Deciduous trees are those trees that produce leaves annually and drop those leaves during the winter months. Performing some annual pruning on shade trees, especially when they are young, helps the tree stay healthy and shapes the tree according to the homeowner’s wishes.
First, pruning live branches from trees can be done any time of the year, however, it is best performed in late winter to early spring. During cool temperatures, less threats such as insects and diseases will be present to attack the trees at the open wounds created by the pruning process. By pruning in late winter or spring, the trees will be starting to break dormancy, thus pruning wounds will have a chance to callus over or heal before the trees begin moving sap upward to the branches.
Also, having the leaves removed during the dormant season allows us to see the branch structure and pick out problems that need to be corrected with pruning. This is the time of year when we can be looking over our trees and making mental or physical notes as to what needs to be pruned later in the winter.
Also, we can be preparing our equipment. Good pruning starts with good, sharp pruning equipment that will make clean cuts. Disinfecting pruning equipment with a bleach or alcohol solution in between trees is always a good idea.
When cutting large, heavy branches, use the three-cut method to avoid stripping the tree’s bark when a heavy branch lets loose and drops before being cut completely through. The three-cut method involves cutting up from the bottom of the heavy branch about 8 inches to a foot from the tree trunk and then making a downward cut three to six inches further out on the branch. If the branch snaps under its own weight, the bark stripping will only go as far as the upward cut.
Then, the third cut is made to remove the remaining stub at the trunk by cutting just outside the branch collar with a single cut. The branch collar is that wrinkle of bark surrounding a branch attachment to the trunk. Keeping cuts outside the collar will minimize the size of the wound and speed the healing process.
Remove all dead branches from the tree. Dead wood can be removed any time of the year as the attachment point is usually already sealed off and will not expose live tissue to diseases and insects. Only remove approximately 10 percent of a tree’s live tissue in any one year. Any dead wood that is removed does not count toward your 10 percent.
A tree should have one true leader at the top. If your young tree has a fork at the top, pick what appears to be the healthiest, strongest branch to keep and prune out the other. Also, look for branches that are rubbing on each other and prune out one of the branches. Branches that are broken, have old wounds or visible disease problems such as soft, watery areas known as cankers, should be removed.
Also, look for branches with weak or narrow attachment points. Branches with an angle to the main trunk of less than 40 degrees are good candidates for pruning as those branches will always have a weak attachment point and be the most likely to snap under ice and snow loads or in strong winds.
Your thumb and pinky finger make good examples for determining good and poor branch angles. A branch with an angle similar to your thumb’s angle off of your hand would be a branch with a good, strong attachment. A branch with an angle similar to your pinky would be considered to have a narrow, weak attachment and could snap easily.
Avoid “topping” trees by simply trimming all the upper branches off from the ends. Topping decreases the aesthetics of the tree and stimulates growth of a number of weakly attached branches.
Remember, only cut out about 10 percent of the live tissue in any one year. Some neglected trees may require two or three years of pruning to make the necessary changes.
Finally, we should know our limits and leave difficult or potentially dangerous pruning projects to professionals.
For more pruning information go online to https://bookstore.ksre.ksu.edu/pubs/c550.pdf and read K-State’s publication All About Pruning.
