COLUMBUS — Ohio field crops is causing concern for some northern Ohio farmers, an Ohio State University Extension entomologist said. Some growers have reported finding Asiatic garden beetle grubs that have caused some stand losses, said Ron Hammond.
What’s surprising about this is the grub, which is a species that is more associated with being a minor pest in turf, now appears to be much more damaging to crops than most other grubs, he said.
“The Asiatic garden beetle is a new problem that’s been recently identified in certain parts of Ohio,” Hammond said. “The grub is now considered very aggressive in its feeding habits.”
The Asiatic garden beetle was introduced to the U.S. in the 1920s on the East Coast and has since made its way across the country, he said. The grubs were recently associated as a newer corn pest in northeast Indiana and southwest Michigan from 2006 to 2008, but always in sandier soils and following soybeans.
Some fields in Ohio meet those conditions, Hammond explained.
“We’ve gotten a number of calls from farmers up north who are saying that they’re having serious problems with the grubs,” he said. “This is definitely a growing concern for farmers.”
The grubs feed on corn roots in the spring, causing stand reductions. Much of the damage Ohio growers have reported has been in corn following soybeans, Hammond said.
Asiatic garden beetle grubs are smaller than other grubs, such as true white grubs and Japanese beetle grubs, Hammond said. The main characteristics to identify Asiatic garden beetle grubs are the enlarged maxillary palps on the side of their mouthparts, he said.
While growers should scout their fields for the grubs, there really isn’t much that can be done to mitigate the grubs once they’ve begun feeding in the soil and causing stand reductions, Hammond said. Because this is a relatively new pest, there aren’t any rescue treatments available, which is usually the case with other grub issues.
One way to monitor for the number of Asiatic garden beetle adults in a field is to observe dead beetle carcasses around brightly lit canopies and ornamental plantings. Elevated numbers can lead to a greater chance of Asiatic garden beetle white grub feeding damage.
“None of the infested fields over the years appear to have been completely protected by the various seed treatments,” he said. “The grubs have to be managed prior to planting with a soil insecticide if growers already have them in the soils in their fields.
“The only action growers could take would be replanting if necessary.”