Q. My trees have brown branches all over them. What is this? What can I do to save them?
Mary from Lisbon
A. What you are experiencing is an act of nature due to the emergence of the 17-year cicada here in Northeast Ohio.
There is one positive thing that can be said about the invasion of Brood VIII cicadas that emerge once every 17 years – they must be patriotic. How else can one explain the numerous flags with which they decorate our trees just in time for Independence Day.
This “flagging” occurs when a fertilized female cicada uses her ovipositor to make slits in a pencil-sized tree or shrub branch in which she lays her eggs.
The branch splits and hangs downward, and the foliage beyond the wound dies, giving it the appearance of a brown pennant. While there are 270 species of plants that are preferred during this assault, favored trees include maple, oak, hickory, beech, ash dogwood, hawthorn, magnolia, willow, apple, peach, cherry and pear.
The shrubs and bushes most often suffering damage are Rose of Sharon, rose, raspberry, grape, black-eyed Susan, hollies, spirea, rhododendron, viburnum, junipers and arborvitae. This damage can make oaks more susceptible to oak wilt this time of year.
A fertilized female can deposit eggs on multiple branches, 20-28 per location, totaling up to 400-600 eggs. According to OSU Extension, six to 10 weeks later (around Canfield Fair time), the white antlike nymphs hatch and drop to the ground.
These nymphs burrow down 6 to 18 inches and begin feeding on tree and shrub roots. Over time, the nymphs can reach depths of 1 to 8 feet.
Harm to mature plants is minimal. I have a very old white oak that at this time has about 100 broken branches, and an 8-year-old New American Elm is flying about two dozen banners. Both should be OK, and I haven’t noticed any problems with my Rose of Sharon bushes.
For details, check out http://go.osu.edu/cicadas.
Dave Campana, an Ohio certified volunteer naturalist in Mahoning County, provided today’s answer. Call 330-533-5538 to submit your questions. Regular clinic hours are 9 a.m. to noon Mondays and Thursdays.