What a summer this has been for our trees! Straight line winds, drought, insect damage and lightning have made a mess out of some of our trees. We lost the top of a magnificent white pine, had dozens snapped off half way up, many large limbs broken and quite a few tip overs.
Many of you who have had this kind of damage may already have removed the most seriously damaged. How about those you are not sure about? Recognizing what can be repaired or healed, what cannot, and when to call a professional will allow the homeowner to save trees that would otherwise be lost.
Some lightning strikes are easy to recognize. (Wait until the storm has passed before going out!) Trees can explode from the vaporization of sap or resin or may even ignite. Needless to say, these trees usually have to come down. Lightning may strip the bark off one side of the trunk or in a spiral down the trunk and blow off a couple limbs. In other strikes, the damage may all be internal; these are the most difficult to diagnose.
A tree that has been struck, whether deciduous or coniferous, may not show the effects of the damage for up to six months when the leaves or needles start to turn brown prematurely. Usually there is no saving these trees. However, as you wait, you can take steps to save a tree that would otherwise be lost. Lightning heats the tissues of a tree or can burn off root hairs below the ground causing the tree to go into stress. Ample watering and the application of fertilizer with high nitrogen levels can help the tree heal damage, if not too severe.
Limbs damaged from wind need to be pruned off so the tree can form a healing collar around the wound. Use normal pruning cuts, being careful not to cut to close to the trunk or limb. Pruning sealers are usually not needed. Allow the tree to heal naturally. The only time to consider painting a wound is on oaks cut in April, May, or June. The beetle that transmits disease to the oak tree is active then and is attracted to the smell of a fresh wound. Only use latex paint, never oil based products.
Tree uprooted by wind can sometimes be saved if the tree is not too large and you act quickly. Carefully dig away the soil on the side away from the fall avoiding further damage to any roots. The tree may be winched or pulled erect with a well-padded rope or chain and the soil replaced around the roots, no deeper than the original level of the roots. Then stake the tree. Water, water, water for the rest of the season and hope.
Trees already weakened by disease or insects are least likely to survive storm damage. Birch with leafless tips are likely infested with birch borers. A pine that yellows prematurely may be infested with bark beetles. Elms with curled and yellowing leaves may be infected with Dutch elm disease.
If damage from lightning or wind is in the crown of a mature tree or the tree is a cherished specimen, you need the services of a professional arborist with the proper equipment and experience to know when a tree can be salvaged. Many homeowners are needlessly injured or killed trying to remove a limb or tree without proper equipment or safety measures.
For further information on tree care and pruning, check the University of Minnesota website: www1.extension.umn.edu/garden. For help with gardening questions, call 444-7916, leaving your name, number, and question. A local master gardener will call to assist you.
