Many people are afraid to prune or cut trees for fear of damaging or killing them. This fear prevents them from making simple corrections when they’re easy to make. The worst tree defects can be fixed, without climbing, when your trees are still young. There are some simple and easy steps you can take to train young trees. First you have to know enough to spot structural problems before it’s too late to fix them.
An easy problem to spot is two competing trunks (called co-dominant leaders by arborists). This is where, instead of one straight trunk, a tree has two side by side. We refer to this as a “wishbone” on the central trunk, and it’s a really bad flaw. On young trees, it’s very easy to fix. If you spot this early you can just cut off the weaker trunk and the other one will take over and grow straight.
A variation on this is where there are multiple trunks from the ground up. Again, simply cut off all but the strongest and straightest one, right at the ground, and you’ve fixed the problem. The remaining trunk will now get all the food and water, and will thrive.
Another common defect to look for is called a “bark-included crotch”. This defect occurs when, instead of a healthy limb attached to the trunk, a tree forms a close crotch (see illustration). As the tree grows, bark is “included” between the limb and trunk, or the tree forms competing trunks with bark between them. The limb and trunk are not really attached, since the bark forms a seam down inside the tree. As the tree grows and the limb or second trunk gets heavier, this hidden weakness becomes more dangerous. The tree may simply split in half by gravity, but usually it’s an ice storm or heavy wind that finally sends the limb crashing down.
The best and easiest time to fix bark-included crotches is when they first occur on young trees, before the limb is thicker than your thumb. You can simply cut the offending limb off at the crotch and it will heal over in a single season. Bigger limbs are harder to cut through and take longer to heal, but the longer you wait the worse the problem. Deal with it now.
To cut tree limbs properly make three cuts: 1. Make a cut on the underside of the limb an inch or two above the spot where it meets the trunk. This will prevent tearing or peeling of the bark when you cut the limb off. 2. Cut downward from above, a few inches further out on the limb, until it falls. This will leave a short stub. 3. Cut the stub off.
Make the final cut straight across the remaining limb, not parallel to the trunk. The exposed end should be round, not oval. Leave enough of a stub so that you don’t damage the “branching collar”; the wrinkled flare of bark around the base of the limb. This will then grow and quickly cover the open cut. Never leave a stub longer than a half-inch, because the bark can’t heal over your cut and this invites many tree problems.
The reason for cutting in three steps is that you can’t cut at the correct angle from above, because the tree trunk interferes with your saw. The final cut has to be made from below. The heavy branch will cause your saw to bind in the cut and get stuck. By cutting most of the limb off first, you take the weight off so you can make the final cut easily and precisely.
Winter is the best time to prune trees. In winter it’s easy to spot where the problems are, and winter pruning is not harmful to trees because they are dormant. Cuts made in winter are less vulnerable to insect infestation, and will begin healing right away in the upcoming season. Remember “a stitch in time saves nine”? Get over your fear and you’ll actually have healthier, stronger trees. You’ll be amazed how proper pruning cuts heal over without a trace. Once you see this work you’ll be proud of yourself.
Steve Boehme is a landscape designer/installer specializing in landscape “makeovers”. “Let’s Grow” is published weekly; column archives are on the “Garden Advice” page at www.goodseedfarm.com. For more information is available at www.goodseedfarm.com or call GoodSeed Farm Landscapes at (937) 587-7021.