Last week’s ice storm was one for the ages, and one we will be seeing the effects of for years. This includes the damage to many landscape and woodland trees. I would like to share with you some information from Bill Fountain, Extension professor in arboriculture about the situation.
What to do when branches are broken depends on may factors. When we look at the physical failures of trees, some species fail more frequently than other species. The specific way trees fail is also very species specific. Once a tree has failed, it is more likely to fail again at some point in the future. If the tree has suffered extensive damage and there is a high value target like a play area, home or driveway, it may be better to remove it and avoid the potential for future problems. If only a side branch has broken it can generally be removed without increasing the risk of future failures. While a hole may remain, it is better to have a slightly defective tree than to be without any tree. While advice from a professional arborist is valuable, the ultimate decision must rest with the owner of the tree.
Restoration pruning is the term used for the multi-year process of restoring the natural shape for a damaged tree. The form will never be the same as what it would have been. The objective is to make the tree more attractive and reduce the risk of future failures. Risk can never be reduced to zero.
If a portion of the central leader has broken, it should be trimmed back to a lateral branch that is at least a third the diameter of the broken terminal. Preference should be given to lateral branches that are more upright but do not have included bark. Pruning back to a lateral that is too small will not have sufficient foliage to result in rapid wound closure. However, in catastrophic events such as ice storms we may have no choice but to prune to smaller laterals. If the tree is young and the side branch being trained into a new lateral is small, the lateral branch can be splinted to encourage upright growth. With time this lateral branch will form a new terminal. If splinting is done it is important that it be done in such a manner that girdling does not occur. Nylon stockings or cloth strips are sometimes used for holding the branch to the splint. Wires, even with a piece of hose pipe are never recommended.
It is not feasible or desirable to remove every damaged tree. The decision making objective is to remove the most damaged trees that present the highest risk for causing future property damage; provide mitigation for those that can be saved. Of those that receive restoration pruning, some will be destined for removal in the future as replacement trees reach sufficient size to be functional entities in the landscape.
The most frequently asked question about pruning is, “What is the best time of the year to prune?” The way a branch is removed is far more important in wound closure and future health of the tree than time of year. Maples, elms, birch, yellowwood and most conifers pruned at this time of year are going to bleed from these open wounds. Sap flow from wounds has never been shown to devitalize the plant. The sugary sap may attract bees. This is not a problem. On cold nights in spring a maple icicle may form. These are more of a curiosity than a problem with the more daring of us tasting the sweet sap of the maples.