February 13, 2009

Home and business owners throughout Kentucky are dealing with the aftereffects of a brutal, late January ice storm that severely damaged landscape trees. Bill Fountain, University of Kentucky horticulture specialist, offered some insight for those cleaning up the mess and planning for the future.

"I'm reminded of a Thomas Edison quote, after he lost his invention factory to a fire in 1914," Fountain said. "The next morning, Edison stood among the ruins and remarked to his associates, ‘All of our mistakes have been destroyed. In a new factory, we can start our experiments with a clean slate.' In looking forward, this ice storm is a chance for us to replace many of the less desirable trees that have been damaged."

Damage was widespread among tree species; however, river birches, silver maples, ornamental pears and willows seem to have suffered disproportionally more damage than other species. Fountain said these are often referred to as the "cheap" trees. They grow rapidly, reproduce early and live a short life, he said. Since the wood they produce is not as strong, they are usually the first to fail.

"The Methuselah trees, like the oaks, are long lived," Fountain said. "They invest their energy reserves in slower growth that is more durable, with reproduction starting at a later age. As you begin to think about replanting this spring, look at the slower growing trees. Bradford pears are beautiful when they are in bloom, but they are not worthy of planting because of their short life span and their potential for causing damage when they fail."

Before home and business owners can think about planting trees this spring, they first have a daunting job in cleaning up the branches of ice-damaged trees and trying to save those that received less damage in the landscape.

Fountain said there are several ways to deal with broken branches, but first it's important to determine the way the tree failed and decide if the tree can be restored, or if it needs to be completely removed from the landscape.

"Once a tree has failed, it is more likely to fail again at some point in the future," he said. "If the tree has suffered extensive damage and there is a high-value target nearby, like a play area, home or driveway, it may be better to remove the tree and void the potential for future problems. But, if only a side branch has broken, you can generally remove it without increasing the risk of future failure."

Professional arborists use the term "restoration pruning" to describe a multi-year process of naturally restoring a tree. The form never will be the same as what it would have been before receiving damage, but the goal is to make the tree more attractive and to reduce the risk of future failure. Fountain said risk can never be reduced to zero.

So what's the best way to begin pruning? Fountain said that 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.

"You should give preference to the lateral branches that are more upright but do not have included bark," he said. "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, the lateral branch will form a new terminal. If splinting is done, it is important that it be done in such a manner that girdling (removing bark) does not occur. Nylon stockings or cloth strips sometimes provide a way to hold the branch to the splint. Don't use wires, even with a piece of hose pipe, Fountain said.

"It's just not feasible or even desirable to remove every damaged tree," he said. "Your goal needs to be to remove the most damaged trees that present the highest risk for causing future property damage."

Fountain went on to say, of those trees that receive restoration pruning, some will be destined for removal in the future as replacement trees reach sufficient size to be functional in the landscape.

And what about choosing replacement trees for the landscape? Fountain explained that owners should think long-term success, rather than short-term gratification.

"People are impatient," he said. "We want our trees to grow rapidly, and then we are perplexed when they don't live very long, in this case breaking apart in an ice storm. Mother Nature is showing us the error of our ways. We have planted our home landscapes and urban areas with too many species that grow too fast. Yes, river birch, silver maple and willows are attractive, but we certainly overuse them and grow them in ways and places that their genetics did not engineer them for."

Fountain said white pines also suffered extensive damage during the storm.

"Yes, they grow rapidly, are great on a landscaping budget, and they are listed as Kentucky native trees," he said. "But they are overused and are really more suited and more common as a northern species. It characteristically grows in a forest where it is adjacent to other white pines that protect it. As a result, it does not produce the large number of lateral branches we see in more open landscapes and it's mainly those side branches that fail under heavy loads of ice."

            Other tree species that are not well-suited to a climate prone to freezing rain and icing are pin oaks and broadleaf evergreens like southern magnolias. These trees retain live leaves throughout the winter and that extra leaf surface allows more area for freezing rain to collect. The added weight is more than enough to result in limb failure.

            "Spring is a time of renewal and a traditional time for planting," Fountain said. "This year, make a resolution to plant a new tree. As you begin to select trees for your landscape, look for durable, long-lived species. Amid the destruction, it's important to recognize the many important environmental benefits our big green companions contribute to our comfort and way of life. I believe that trees, more than any other single factor, are what make our homes and cities livable."