Corrective Pruning after the 17-year Cicada

John W. Jett Ph.D.
WVU Extension Service
Horticulture Specialist
8/99

Now that the 17-year cicada have come and gone, your attention may be turning to the damage they caused to your ornamental plantings and what you can do to restore the aesthetic value of those plants.

Brood V of the periodical cicada appeared several weeks ago in the upper two-thirds of West Virginia. The damage caused during the egg-laying process of the female cicada is now evident not only in deciduous woodlots but also on ornamental trees and shrubs around the home.

The ovipositing slits on 1- and 2-year-old wood, which partially or totally girdles these branches, cause "flagging" or breakage to the tips of these branches. With the exception of very small plants the damage is only a brief interruption in normal plant growth, which can be put back on track with well-placed pruning cuts. Small plants with extensive branch kill may need to be replaced.

With the obvious distinction between dead and living tissue, now might be a good time to prune all brown and withered branches. However, with drought or near-drought conditions covering Brood V terrain, it may be better to delay pruning until late fall or early spring. With additional stress on plants due to the lack of soil moisture, plant dieback may progress further down the damaged branch.

When removing damage on 1-year-old wood, make your pruning cut into healthy tissue (determined by green internal color) just in front of a bud facing to the outside of the plant (Figure 1).

When removing 2-year-old or older wood, make your cuts just in front of healthy side branches that are growing toward the outside of the plant (Figure 2). Some additional thinning and shaping may be needed during the pruning process to restore the plant to its natural form.

With pruning and development of next year's growth, the damage caused by the Brood V cicada will be history until the year 2016.