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Some tips on how to care for damaged trees

The severe ice storm of 1998 caused damage to many trees in eastern Canada. Ice storms are common events in the region, so trees are remarkably resilient. Trees that have not suffered major structural damage, such as split trunks, will recover with time. Trees are dormant in the winter and damage at that time of year is less serious than if the damage occurs during the growing season. If a tree is reasonably healthy and only a moderate number of branches are damaged or removed, the tree should recover and in a few years the crown or tree top will probably appear normal. Again, this depends on the tree health and the extent of damage. Every tree is different!

Assessing the Damage

Trees are a familiar and pleasant feature of the urban landscape in parks and green areas, and specimen trees are highly valued by home owners and local residents. Most damaged trees can probably be saved with appropriate treatment. It is usually worthwhile to care for the damaged tree now and wait until the growing season to see if it recovers. Methods of care are outlined below.

Many young trees, especially those with thin stems, have been bent over to ground-level by the weight of the ice collected on their crowns. Trees at this stage of development are quite flexible, and most will recover and regain an upright position when the ice weighing them down melts away. It is best to wait for above-freezing temperatures to attempt to remove ice from trees. Attempting to do so while ice is still firmly attached will lead to bark damage and removal of buds that will produce new growth in the spring.

Given the severity of the ice storm, any age, species or size of tree may have been damaged. In general, however, coniferous trees like spruces and firs have suffered much less damage than deciduous species. Most conifer species have developed narrow crowns and short, upright branches that minimize ice and snow loading. Damage to deciduous tree species has been much more severe. Trees with soft or brittle wood like Manitoba maple, silver maple, native and European birches and Siberian elms are particularly affected. Oaks, hickories and ginkgo trees, all species with strong wood and well attached branches, suffered less structural damage.

Caring for Damaged Trees ... Safety First!

The many large, broken and icy branches hanging from trees are an extreme danger. Please be careful working near or under any damaged tree. Branches that appear to be well wedged in the crown can fall without warning at any time, resulting in serious bodily harm and damage to property. Please do not go near any tree close to power lines. Approach and inspect damaged trees only if it is clearly safe to do so. Pruning of large branches and stems is difficult and hazardous and should only be carried out by persons trained and experienced in such work.

Proper Pruning

Properly conducted pruning is not harmful to trees; injuries are usually caused by haste, improper tools, or eliminating too much of the live crown. Pruning should be conducted on limbs with open breaks. As well, damaged trees should be closely inspected and for cracks and fissures at the base of large branches and stems. Often these cracks will have closed following damage, making them difficult to see.

The key to recovery after damage is proper branch stub pruning. Try not to leave a long broken stub as this will prevent the wound from healing. Conversely, do not prune flush to the main stem as this creates a large hole that will be slow to heal. The best place to prune any branch is at the branch collar, generally observed as a swelling or "turtleneck" of bark about 2-3 cm above the branch base. Trimming here will result in a wound that closes quickly and completely. Try to ensure your cut is at an angle that prevents water from entering or pooling in the affected area. It may only be necessary to prune away part of a branch if damage is located far from the branch base. If this is the case, select a healthy secondary branch that can take over growth of the main branch, and prune just beyond that point.

Do not cover pruning wounds with prepared compounds. Trees have their own protection mechanisms that will efficiently seal the wound.

The loss of living branches has in many cases resulted in a long strips of bark being torn away from the trunks of trees and from the underside of large branches. This damage is unsightly, but given time, a healthy tree is capable of sealing even very large wounds. Loose and torn bark around a wound of this type will offer a favorable site for water, insects and disease to enter the tree during the healing process. It is best to cut back loose bark to the edge of a wound, taking care not to expand the damaged area unnecessarily.

Replacing Severely Damaged Trees

If a tree has to be removed completely, now is a good time to consider suitable choices for replacement trees. As stated previously, certain species are predisposed to structural failure and branch loss. Thus, planting these trees should be avoided. When planted in open areas, most deciduous trees will try to take advantage of the space around them by developing low horizontal branches and multiple stems. These features are weak points that lead to severe damage in ice storms. Removal of low branches and multiple stems while they are still small is a simple task that can greatly reduce the risk of damage in future. Special columnar varieties do exist for many species including oaks, Norway maple and even ginkgo. These forms do not produce spreading branches and are best suited to limited space in urban areas and near utility lines.

Conifers are good choices, but become broad at the base as they mature. In tight urban spaces, slow-growing or dwarf varieties are increasingly popular. Now is also the time to consider location. Avoiding placement of trees in and around utility lines will make a big difference in the future should an ice storm like that of 1998 occur again.

Please note: This information is only intended to assist those with basic tree care and recovery. We urge you not to risk your safety by attempting to remove limbs beyond your capacity or expertise. Any tree or branches near hydro-electric lines should not be approached. Should you be uncertain about such action, please be patient and local authorities will assist you.

If you have more specific questions, please contact your local tree nursery for help and advice on tree care.