Purdue Extension Service

Vanderburgh County, Indiana

Wind Damage Causing Confusing Symptoms

By Larry Caplan, Extension Horticulture Educator, Vanderburgh County, IN

For the Evansville Courier and Press, May 30, 2008

I've had several calls lately about trees showing numerous dead twigs throughout the canopy. The tips of the branches appear to be wilting and drooping, although the twigs and foliage deeper within the tree appear fine. It is usually worse on one side of the tree than the other.

After closely examining a few of these twigs with a magnifier, I could see no signs of insects or their feeding. No nibbles on the stem, like I'd expect to see from an insect called the twig girdler. No teeth marks, as I'd expect to see if squirrels were chewing on the twigs. No hollow or bored out shoots, such as those caused by various shoot borers. And no egg-laying damage from cicadas.

What I did see were twigs bent at a single spot (usually), with the stem tissue twisted. There was more damage on one side of the tree (the west side). This is consistent with the type of damage I'd expect to see from high wind. You may recall that we had some extremely "brisk" wind storms earlier in May, especially during Mother's Day weekend. Many trees were still leafing out at this point, and were especially delicate and prone to injury.

High winds often cause a great deal of limb breakage. Usually, we see larger branches fall out of the trees, especially if they've previously been damaged and begun to decay. Some limbs will tear out of a tree if they were growing at too tight an angle to the trunk. These narrow crotches are not as strong and flexible as wide, U-shaped branch crotches, and are more likely to fall out.

Small twigs may wilt, droop, and drop out of the tree up to a year after the tree was visited by periodical (17-year) cicadas. The female cicada will puncture or slit the twigs of trees or shrubs and lay her eggs in the wound. The zipper-like injury sometimes weakens the stem enough to kill off the growth, and eventually drop off the tree. In theory, we should be in the midst of the Brood XIV cicada emergence, which is supposed to be heaviest in southwestern Indiana. However, I've had no reports of cicadas from anywhere near the tri-state. If you see (or better yet, hear) cicadas over the next three or four weeks, please let me know.

The twigs that were damaged by the wind earlier this month will eventually die and fall out of the tree. The trees I've examined have already starting sprouting more foliage, so this isn't going to hurt the trees at all. No specific action is needed at this time. However, if you do plan on pruning your trees in the next few years, be sure to have them pruned correctly to eliminate week limbs and to prevent decay of the branches and trunk.

For more information on storm damage, cicadas, and trees, contact the Purdue Extension Service at (812) 435-5287.