I took the opportunity during the sunny weather last weekend to do some pruning on my trees. Actually, I recruited my dad to help me do some pruning. I pointed and he cut, and I certainly got the better end of the deal.
January is a great time to prune because many of our trees have lost their leaves, making it easy to see the limb structure. Late winter is a good time to prune for the health of the tree because it is right before they put on new growth. You do not want to prune late in the spring after the new growth comes out because a tree uses a lot of its stored energy to put on new growth. Pruning off the new growth can stunt the tree.
When you prune, be sure to make clean, smooth cuts. Do not leave stubs and avoid tearing the bark. When cutting heavy branches, use a three-part cut. Saw an undercut from the bottom of the branch about six to 12 inches out from the trunk and about one third of the way up through the branch. Then make a second cut from the top, about three inches further from the trunk. This undercut will stop the bark from peeling when you make the second cut. The second cut removes a lot of weight from the branch so you can make a clean third cut. Use the third cut to remove the stub back to the branch collar.
The branch collar on trees is an interesting intersection. The branch collar is the swollen area of trunk tissue that forms around the base of a branch. The collar is an area of tissue that contains a chemically protected zone. In the natural process of decay on a dead branch, the decay advances downward until it meets this protected zone in the branch collar. The dead branch falls away at the collar, leaving a very small zone of decayed wood in the collar that the tree can wall off. What a neat natural protective process for the tree!
A good pruning cut is not flush with the trunk but is slightly angled to avoid the branch collar. Leave the branch collar so the tree can quickly wall off the damage from the cut and heal over the wound. You can tell a tree is covering over a wound when the rounded edge starts growing over the cut.
A lot of folks want to use pruning paint to help trees heal quickly. Research shows that pruning paint can slow down the healing process. We only recommend painting your cuts on oak trees to prevent the spread of oak wilt through the Nitidulid beetle. When pruning oaks, paint the wounds within 15 minutes of making the cut.
Some pruning jobs require the help of professionals, for your safety and the safety of whatever might be underneath a large branch. For big jobs, I recommend hiring a certified arborist who can help you determine what to prune and do it correctly.
For more information on lawn and garden topics, contact Kate Whitney, Horticulture Extension Agent, at 512-943-3300.