Melvin R. Koelling Department of Forestry Michigan State University,
Russell P. Kidd Department of Forestry Michigan State University
When storms strike, along with damage to property such as houses, power lines, and commercial buildings, they may cause damage to trees in the urban forest. There are six main types of storm damage to trees: 1) blow-over, 2) stem failure, 3) crown twist, 4) root failure, 5) branch failure, and 6) lightning. Each type is the result of a complex and interactive mix of tree problems and climate.
Damage is often relatively minor with only the smallest braches of the tree being injured. Usually damages of this type result in little or no permanent damage to the tree. All that is required is clean up of the broken twigs and branches and perhaps some light pruning to restore a pleasing shape.
Severe damage consisting of large broken branches, split crotches and removal of bark, and splitting or splintering of the trunk can also occur. Strong winds, lightning and heavy ice storms are the most probable causes. When a tree is severely damaged, the first question that must be answered is: “Is the condition of the tree such to make keeping it worthwhile?” Take the time and effort to save a tree only if a substantial portion of the tree remains intact and if, when repairs are made, the tree will still be attractive and of value to the property owner.
Treating the tree
Assuming the decision has been made to repair the tree, the next question is: “Am I capable of repairing the damage myself or should I seek professional help?” Unless experienced in the use of such equipment and comfortable working off the ground, it may be best to have the work performed by a competent professional. Once it has been determined that a tree can be salvaged there are certain procedures that one should follow.
- Assess the damage. Some branches may be broken and hanging in the tree, others may be partially attached, and in some cases, entire forks may be split.
- Plan which branches must be removed and where the removal cut should be made.
- Remove all damaged branches at the nearest lateral branch, bud, or main stem and not in the middle of a branch.
Branches smaller than 3-inches in diameter can be removed using pruning shears or a pole-pruner. Sharp, properly aligned shears or pruners will make a clean cut, not crush or tear bark tissue and reduce cleanup time. Use a sharp saw to remove larger branches. If a power saw is used, a safety rope and harness are essential. The most efficient and least damaging way to remove large branches without causing further damage to the tree is the 3-cut procedure. The first cut is the undercut. From the underside, saw approximately 12 to 18 inches from the main stem or branch to which the damage limb is attached. Cut into the branch about 1 to 1½ inches deep and withdraw the saw blade before it begins to bind. For the second cut, or over cut, saw approximately 2 to 3 inches beyond the undercut and continue until the branch is removed. The final or flush cut is made to remove the remaining stub. Saw in the natural depression flush with the trunk or branches. Careless pruning can result in death of the entire branch or in excessive sprouting and the eventual development of more problems later on, since these sprouts are generally short lived and weakly attached.
In some instances the tearing of bark on large limbs or the main trunk occurs. This is especially common when trees have been struck by lightning. Carefully trim away all loose bark back to the area where it is solidly attached. Do not cut too deeply into the wood of the tree. This cutting of the bark is referred to as a bark tracing. If possible, all bark wounds should be cut into an elliptical shape, being careful to keep the trace as narrow as possible. This may be difficult on large areas. However, trimming the bark in this manner will encourage rapid healing with minimal wood decay.
Some forks and main branches that are split apart or partially broken may be repaired without removing one or both branches. This type of work is usually beyond the capability of most homeowners unless they have experienced assistance. If the break is nearly even, it is possible to draw the split portions back together and secure them with a large diameter steel bolt and threaded screw rod placed through the split section. The proper procedure for repair begins with drawing the split together using a small block and tackle or winch. Place this 6 to 8 feet or more above the split to obtain maximum leverage. Drill holes through both halves of the split in which the bolt or rod is inserted. With long split areas, 2 or more bolts may be necessary. In addition to the bolts, it often helps to install a steel cable between the two main braches of the split fork several feet above the split. Use lag screws to attach the cable to each branch. Do not wrap the cable around the branch or it may eventually girdle it. This cable system helps hold the crotch together, thus reducing the chance of further breakage.
After pruning is complete, all wounds larger than 1½ to 2 inches in diameter can be coated with wound dressing or pruning paint. Recent research has shown that dressings and paints probably do not increase the rate of healing. However, they may prevent drying out and provide some cosmetic effect. Several commercial materials are available or a couple of coats of orange shellac suffice. Areas of torn bark where tracings have been made can also be treated in this manner.
Trees may be uprooted as a result of severe storms. If the tree is large, it cannot be saved and therefore must be removed. For some smaller trees it may be possible to straighten the tree and brace it using guy wires or cables. Some type of power lift or equipment is usually necessary to pull the tree upright. Do not attempt this procedure unless 1/3 to 1/2 of the roots are still in the soil and the remaining exposed roots are relatively compact and undisturbed.
Before the tree is pulled upright, remove some soil from beneath the root mass so the roots will be placed below the existing soil grade level. Once the tree is back in the upright position, fill in soil as needed. Water the tree to help firm the soil and remove air pockets. Attach 2 or 3 guy lines to the trunk as is often done for newly transplanted trees, at a point approximately two-thirds of the height of the tree and to anchors placed some 12 to 15 feet from the base of the tree to hold the tree in place.
Materials from fallen or salvaged trees can be used in several ways. The larger branches can be cut and used for firewood. Add smaller branches and twigs to the compost pile or cut up for kindling. Branches can also be converted into chips for use as compost, mulch or other landscaping purposes if chipping equipment is available to local residents.
Melvin.R Koelling and Russell P. Kidd, MSU Forestry Department, Extension Bulletin E-1364
Mary L. Duryea, Ph.D., forest resource extension specialist, School of Forest Resources and Conservation, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611
Manfred E. Mielke, Plant Pathologist Northeastern Area, Forest Health Protection, USDA Forest Service, St. Paul, Minnesota 55108
Margery L. Daughtry, Extension Associate, Department of Plant Pathology, Cornell University, L.I. Hort. Research Lab, Riverhead, New York 11901