Question: Last week's windstorm really damaged several of the trees in our landscape. One entire side of our large maple fell off, while several large branches have broken off from another tree, but still remain attached to the main trunk. Our neighbor told us we should just cut the trees down. What do you suggest we do?
Answer: Homeowners are often amazed when trees that appear to be healthy with plenty of foliage suffer major damage during a windstorm. More often than not, when a large limb or entire tree comes crashing down, inside portions of that limb or trunk are usually revealed to be rotten. The internal wood may be soft, dark in color, or completely hollowed out. These symptoms are all caused by wood rot fungus diseases that more than likely infected the tree in previous years through wounds to the trunk, improper pruning or storm related damage.
The puzzling part of this is that many trees have no visible symptoms of internal decay problems. Once wind damage has occurred however, the damage becomes very visible. Keep in mind the vascular system of trees is just under the bark, so trees infected with wood rot can appear fine because water and nutrient exchange continues between the leaves and the roots.
However, as wood rot fungi invade the heartwood, or center wood of the trunk, trees become structurally weakened. Depending on the tree species and the fungus disease, some trees can live for years with no visible symptoms of internal decay. Once a tree is infected with rot, it is almost impossible to control it and usually the best advice is to remove the tree.
Trees that have broken limbs not infected with decay can usually be repaired with proper pruning. Generally, if the branch has not split away from the trunk, the broken segment should be removed back to the next major branch. Do not leave branch stubs since they encourage rot and decay.
To avoid stripping the healthy bark from the trunk when a heavy, broken limb is removed, the three-step procedure should be used. The first cut is made on the underneath side of the branch about 18 inches out from the trunk. The cut should be approximately half-way through the branch or until its weight first starts to bind the saw. The next cut should be made on top of the branch about 1 to 2 inches in front (toward the end of the branch) of the bottom cut. Continue cutting until the branch drops free. The last cut removes the remaining branch stub from the trunk. The cut should be made from the top of the branch at the branch collar. The branch collar is the slight ridge where the branch attaches to the tree's trunk or another major branch.
In certain situations, a damaged limb may strip healthy bark from the tree. To repair this type of damage, cut any ragged edges of torn bark away from the damaged area. Take care to limit the amount of healthy, tight bark removed. To speed the healing process, the repair cut, which is made with a sharp knife into healthy bark, should leave a wound shaped like an elongated football. The pointed ends of the cut should run vertically along the trunk or limb or as near parallel to the initial damage as possible.
Treatment of the trunk and limb wounds with tree paint is not necessary. In fact, research shows that painted areas can lead to increased rot and decay due to trapped moisture in areas where the paint cracks open.
An on-going inspection of trees in your landscape will help to prevent potential storm-damage problems. Often, trees infected with wood rot will produce fungus structures commonly referred to as "conks." These are highly visible and often increase in size as the decay progresses. Other symptoms of wood rot include missing bark and discolored areas on a trunk or branch.
Take a good look at the ornamental trees in your landscape. After the winds of last week, broken branches may need to be pruned out. There also may be broken stubs left that need to be pruned correctly. Addressing these pruning chores now will greatly reduce the potential for wood rot.
EDITOR'S NOTE: For answers to local gardening questions, contact Master Gardener Rachel Gana at 642-8723 or e-mail her at: firstname.lastname@example.org.