Lightning can heavily damage trees

The storms of the past few weeks have damaged many trees in our area. I have seen trees that were uprooted and trees that were struck by lightning.

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Storm damage can kill trees as well as make them unsafe. Falling limbs can hurt or kill people and cause serious damage to property, so it is best to remove broken limbs or damaged parts of trees.

Monday afternoon, I was in Edgefield County when a storm struck. Trees and limbs were blown down across the road. I had to go miles out of the way to get home.

What needs to be done with these trees? Large uprooted trees should be removed, but smaller trees can be saved.

An uprooted small tree should be replanted as soon as possible. The tree also needs to be supported with guy wires until it is reestablished.

There may be some dieback at the upper parts of the tree or at the end of limbs. The extent of damage will depend on the amount of root injury the tree has suffered. Prune any broken limbs immediately. The use of sealers or paints is not recommended on pruning cuts. This slows down the healing process.

Also, trees need to be mulched and watered, especially during additional periods of stress, such as drought.

There are several things that can be done to reduce wind damage to trees. First, help newly planted trees adjust to their new location by properly staking and guying them for a short period of time, no more than a year. Always stake and tie the tree relatively loosely so the stem can move and bend in the wind. This will make the trunk of the tree stronger.

Remember, stakes and guy wires are only temporary and must be removed as soon as the tree is established. As a general rule, remove guy wires by mid-spring from trees planted the previous fall or winter, and eight to 10 weeks after transplanting in spring and summer.

Wind damage can also be reduced by not overfertilizing the plant with nitrogen, which can promote top-heavy leaf growth. Also, avoid overwatering. Plants growing in excessively wet soil may fall, especially after a long period of rain when the soil no longer gives good support.

Trees growing upright with one main stem are stronger and less likely to break than trees with multiple stems. Trees such as Bradford pears split apart when the crotch angles become too narrow. Limbs or stems with narrow crotch angles need to be removed when they are small.

Tall trees and those growing in open locations are very susceptible to lightning damage. A tree that has been struck by lightning can have many symptoms. Some trees immediately burst into flames and explode when they are hit, and others show no damage until a later time.

Typically, strips of bark extending down the trunk or branches are loosened or burned and might hang from the tree. A wide band might be affected surrounding the entire tree cylinder. Extensive root damage from the electrical current that moved through the tree will not be apparent.

The extent and type of damage determines whether the tree will live. Sometimes, it will take six months to a year to determine whether the tree will survive.

The first step in dealing with lightning-damaged trees is to prune broken branches and remove strips of loose bark. Next, reduce other stresses to the plants, such as dryness or pests. A tree that is weakened by lightning is very susceptible to pests. With pine trees, it is usually pine beetles that kill the tree. They are drawn to the pine sap when the tree is damaged.

The first step in caring for lightning-struck trees is irrigation in dry weather. Lightning can kill the cambium and interrupt the water flow to the top of the tree. Also, stored starch in the wood can be trapped when barrier zones induced by the lightning strike form. This can starve the tree.

Do not heavily fertilize the tree, because this can further reduce its energy reserves. Fertilizers can cause the tree to try to put on new growth that it might not be able to support.

Watch the tree for signs of declining branches, including yellow or dying foliage, then remove dead branches. It can take several years for a tree to fully recover from a lightning strike.

Valuable old trees can be protected with lightning conductors installed by a professional arborist. This is accomplished by attaching a series of copper cables to the tree's highest branches and then grounding them a safe distance from the tree. If lightning strikes the tree, the current flows down the cables and safely to ground.

Charles Phillips, a retired Columbia County Extension Service agent, operates Hort Consulting. He can be reached at cphillipshort@comcast.net.