First Aid for Broken Limbs
By Vincent Lazaneo
Gardeners often wonder what to do when a tree limb breaks during a winter storm or Santa Ana winds. Here are answers to a few common questions.
Q. When a tree limb breaks, what should I do?
A. When a limb breaks, it should be pruned to remove the damaged portion. It can be cut back to a strong lateral branch that is growing in a desirable direction or removed completely where it joins a larger branch or the trunk. Trees can be pruned anytime to remove dead, damaged, weak or diseased branches.
Q. When a branch is removed from the trunk of a tree, how close should the cut be made?
A. Large tree limbs must be cut with a saw. The recommended procedure is to remove a limb in two steps involving three cuts. Make the first cut on the underside of the branch 1 to 2 feet from the crotch and at least one-third of the diameter deep. Make the second cut, a downward one, 1 to 3 inches farther from the crotch than the first cut. The limb should then split cleanly between the two cuts without tearing the bark. The third cut to remove the remaining stub is made at the crotch, but its exact position is important to ensure rapid closure of the wound.
A flush cut close to the trunk should not be used when a larger limb is removed. Most trees form a raised collar (also called branch bark ridges or shoulder ridges) on the top and bottom of branches where they attach to the trunk. The collar tissue promotes faster wound closure and should be retained. When a larger limb is removed, the final cut should be made just beyond the collar tissue. The cut will not be flush or parallel with the trunk, but will be out from it slightly with the lower edge of the cut further away from the trunk than the top one. Such a cut will form a smaller wound than a flush cut and it will close more quickly.
New vigorous shoots called suckers or water sprouts and small branches can be cut close to the trunk or branch from which they arise. This is usually done with a single upward cut using a hand pruner for small shoots and a lopper for branches up to an inch in diameter. The close cut will reduce the growth of new shoots from latent buds on most trees.
Q. Should pruning paint be applied when a tree limb is removed ?
A. No. Protecting pruning cuts with an asphalt emulsion or other coating material is of no value and could be harmful to the tree. Coatings and coverings can trap moisture, increasing the chances of wood decay and retard wound closure. The best practice is to let the wound dry in the air.
Vincent Lazaneo Urban Horticulture Advisor for UC Cooperative Extension. He helped found the San Diego County Master Gardener Association more than two decades ago and serves as its advisor. He is the author of numerous articles on plants and pests that appeared in the San Diego Union-Tribune, California Garden and other publications.
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