Asian longhorned beetles in southwest Ohio
Editors note: Throughout the growing season, Mike Hogan, OSU Extension Educator for Agriculture & Natural Resources in Franklin County, will answer gardening questions submitted by Dispatch readers. Send your questions to hogan.1@osu.edu.
Q: I keep reading that we should be vigilant for Asian longhorned beetles and to report them if we see them. Where should we be looking for these insects?
A: To date, the only location in Ohio where Asian longhorned beetles have been found is in Clermont County in the southwest corner of the state. The invasive pest bores into hardwood trees such as maples, willow, elms, buckeye and birches. Infested trees do not recover and eventually die.
Infested trees will have round exit holes from the pest on the trunk of the tree and in small branches about the diameter of a dime. The beetle has very distinctive markings and is easy to recognize. The insect is fairly large at 1 to 11⁄2 inches long and has black and white antennae that are longer than the insect's body. It has six legs with blue coloration on its feet.
If you suspect the presence of Asian longhorned beetle, contact the Asian longhorned beetle hotline at 1-866-7029938.
Q: Many of the branch tips of our large oak trees have turned brown and died recently. This seemed to happen after the cicadas were here earlier in the summer. Could the damage have been caused by the cicadas?
A: Yes, that sounds like typical damage that occurs after periodical cicada females cut slits into small branches of trees to insert their eggs before they complete their life cycle and die. This causes damage to the vascular system of the branches beyond where these slits are located, causing the sections of foliage on these branches to wilt and die. This typically occurs closer to the tips of the branches rather than toward the interior of the tree canopy. Some of the damaged branches fall to the ground immediately and others remain attached to the tree. These leaves and
branch tips will soon begin to fall to the ground. This damage is mostly aesthetic and should not have any long term effect on the overall health of the tree
Q: We have several tall columnar varieties of sweet gum trees that have developed branches that are drooping. It looks like some of these branches may be broken. Would squirrels be causing this damage or could it be due to something else? Would it be safe to prune these branches at this time of year?
A: We have seen quite a bit of tree damage this summer and much of it can be traced back to the late snowfall that occurred in April after most deciduous trees had completed leaf-out. Although the snowfall would not have caused damage to trees without foliage, the wetter-than-normal snow accumulated on the new leaves causing some branches and limbs to break from the weight, and others to simply bend and become distorted. Many of the smaller branches that appeared to be bent or distorted have recovered, returning to more typical angles and profiles, but some have not. Larger branches that were damaged seem to be recovering much more slowly than smaller branches.
The affected branches that are drooping are not broken if the leaves are still green and alive. These branches could be selectively pruned at this time of year but I would be tempted to wait until next spring to see if they recover. After the leaves fall in a few months, there is a possibility that these drooping branches could return to a more upright position on the tree. If the affected branches are still drooping next spring, you could prune them at that time.