Jennifer Schultz Nelson
Extension Educator, Horticulture
Even if you are not someone with a green thumb, recent winter storms have probably made you take a closer look at your landscape, particularly the trees. Some of you may be more up close and personal with your trees than you ever thought you'd be, as you struggle to remove branches and sometimes whole trees that are blocking your driveway or smashing into cars and buildings, weighted with what seems like a ton of ice.
Undoubtedly, many people in the area are looking at their damaged landscape and wondering "Now what?" After downed limbs are removed from your property, you usually have some remnant of the original tree. Do you try to save it, or cut it down? What needs to be done to save it? Can you do it yourself? The answers to these questions are very case-specific, but there are basic recommendations and resources out there to help you decide.
Ice storms put an incredible amount of stress on trees. Depending on the size of the tree, a coating of ice can increase the branch weight by thirty times or more! Much of this added weight is highly dependent on available surface area. Although many people find a broad, finely branched tree canopy attractive, this is one of the growth habits most susceptible to ice damage.
Branch angle also makes a difference. Extremely low (horizontal) or high (vertical) angles can be more susceptible to damage. A highly branched lateral, or horizontal branch is far more susceptible to ice accumulation and breakage than a more upright, less branched limb. Extremely high branch angles can be weak branches if there is a lot of "included" bark tissue in the crotch of the two branches. This included bark in branch angles is one reason that the once popular 'Bradford' pear is extremely susceptible to storm damage. Branch angles with more bark are not as strong as the same branch angle composed of wood.
Tree health affects storm damage susceptibility. Limbs weakened by stress and disease are more likely to suffer storm damage. Improper pruning, and purposely "topping" trees to encourage fine branching will ultimately produce a tree more susceptible for ice damage. Lots of fine branches are not only weaker than larger branches, but they offer an incredible amount of surface area on which ice can accumulate during a winter storm. This adds up to an incredible amount of weight on a weak structure, increasing the likelihood that the branch will break. Though you may not consider yourself a "gardener", proper pruning of trees is one way to protect your home or other structures on your property.
Proper pruning can be intimidating to homeowners, but there are some simple approaches that work in most situations. Assessing and pruning trees on your property regularly is one pro-active measure you can take to reduce the potential for storm damage.
Pruning is best done during the winter when the tree is dormant. There are many philosophies on the art of pruning, and many publications dedicated to the subject, but for preventing storm damage the primary focus is developing a solid limb structure.
One general approach is to remove crossing branches, as they may rub together and damage each other, remove any vertical twigs, also known as "water sprouts" as these tend to be weak, and remove whole branches whenever possible. If removing a whole branch is not possible, remove the branch up to a sturdy secondary branch. Keep in mind that small twigs create more surface area for ice accumulation.
Remove branches with potential to fall on buildings or across power lines, but keep in mind that in most cases large limb removal is best left to the professionals. My parents had a portion of a large tree fall during a storm and clip the corner of the house. My dad struggled to try and remove the limb from the driveway, but became increasingly frustrated. When he finally relented and called in the professionals, it took the power of a large crane to move the tree limb. It probably wasn't realistic for my dad to think the ol' Cub Cadet tractor could handle the job, but try telling him that.
Removing whole branches, whether through regular pruning or storm damage repair, requires some attention to detail. Look at where the branch joins a larger branch or the trunk of the tree. There is a ridge of tissue that looks like a turtleneck–this is the branch collar. The collar produces plant hormones that promote natural healing at the cut site.
Use the "3-cut" method to prevent injury to the surrounding bark when removing a tree branch. The first cut is made on the bottom side of the branch, about a foot from the base of the section you want to remove. Cut about halfway through the branch, stopping before cutting all the way through. Next cut from the top, completing the cut you began from below. This removes the bulk of the branch targeted for removal. The last cut falls at the branch collar, and removes the remaining "stub" of the branch.
Leaving a large "stub" of branch extending beyond the collar will not promote healing, and will be unsightly. Cutting the branch off flush with the trunk or larger branch will remove the collar and its healing hormones. The resulting cut will take much longer to heal, and is more susceptible to insects and disease. When pruning at the branch collar, cut at an angle that will allow water to drain from the cut site, and not allow it to pool in the cut, which could promote disease. Use of "pruning sealer" or other such products is unnecessary and not recommended. The tree's natural healing ability is best.
When you are forced to deal with trees damaged by storms, it is not necessary to make the decision to try and save or remove the injured tree overnight. Many times the injuries sustained by the tree will take months or even years to become apparent. What does need to be done as soon as possible is to assess the immediate hazards caused by damaged trees. Some of this can be a do-it-yourself adventure, but potentially unstable, very large limbs leaning on objects or involved with power lines should be handled by professionals.
If in doubt, call a certified arborist. It may be tempting to save a few bucks by attempting to remove damaged limbs yourself, or to hire the first person to show up on your doorstep with a saw, but a wrong move that sends someone to the hospital, or sends the remainder of a tree toppling onto your home or car will quickly eat up any money saved. Certified arborists are listed in the phone book, or you are always welcome to call our office at 877-6042 for help in locating one.
One recurring question our office has gotten in the aftermath of the recent ice storm is "Can my tree be saved?" That is a tough question, made even more difficult by the fact that you won't know for sure the extent of damage to a tree until spring arrives. In response to major ice storms that hit the East Coast in 1998, the USDA Forest Service issued guidelines for homeowners in determining whether a tree is likely to recover from storm damage.
Young trees that are bent over and covered in ice should be allowed to naturally thaw and may be later staked to add support. Trying to move an ice-encased young tree will likely crack branches and damage the tree
The likelihood that a tree will survive storm damage is directly connected to the amount of crown lost. Another factor is to what extent is the main trunk affected. In very general terms, a tree with less than 50% of the crown damaged will very likely recover with proper removal and pruning of affected areas.
When 50 to 75% of the crown is damaged, it is a very grey area in terms of likelihood of survival. Damage that is close to the trunk decreases chances of survival. Loss of large branches increases chances for infection by disease and insect damage. Trees should be monitored carefully for signs of disease. Torn bark will potentially harbor insects and disease.
Carfully removing any loose and/or damaged bark will increase the trees chances of recovery. When trimming out damaged bark, use a sharp knife and make cuts in the shape of an elongated football running parallel to the length of the limb or trunk. This shape is much more likely to successfully heal than a jagged cut across the area.
A tree that has more than 75% of the crown damaged is not likely to survive. It is very likely that disease and insects will infect the tree. Plus, there is not enough crown remaining to effectively support the trunk and root system of the tree. It is also extremely likely that a tree damaged to this extent is unstable and presents a hazard in the landscape.
Occasionally there are splits and cracks caused by storm damage that go unnoticed initially. Continue to monitor trees through the growing season and look for symptoms of infection or general decline.
As is true with nature in general, there are always exceptions to the rule. Many times if a pine or other conifer has lost less than 50% of its crown, but the loss includes the top branches of the tree, it will never look the same again. The typical growth pattern of conifers relies on one central leader branch. If lost, a side branch will take over as the new central leader in time, but the result is often very lop-sided. Depending on the trees location and how much its appearance matters, you may choose to remove the tree.
If you need help dealing with your storm damaged trees, please call our office. We are happy to help you assess your situation, and direct you to appropriate professionals if needed. We have several handouts available, including suggestions if cultivars considered resistant to storm damage. U of I Extension has more information on weathering winter storms available at http://web.extension.uiuc.edu/disaster/after.html.