WOOSTER, Ohio – A pest not traditionally known to Ohio corn growers has been found in pockets of the state and, in some cases, has the potential to cause stunted corn and yield loss.
Some Ohio corn growers, particularly those in northern Ohio with fields that contain sandy soils, are finding fields with wilted and stunted corn thanks to an infestation of Asiatic garden beetle grubs, said Andy Michel, an Ohio State University Extension pest expert in the College of Food, Agricultural, and Environmental Sciences.
The grubs are a relatively new pest to Ohio field crops and have the potential to cause significant economic losses for growers, said Michel, who also has an appointment with the Ohio Agricultural Research and Development Center.
OSU Extension and OARDC are the statewide outreach and research arms, respectively, of the college.
The first known instance of the grubs causing significant stand losses in corn occurred in 2012 in northwest Ohio near the Maumee River basin and in northern Ohio just below Lake Erie, Michel said. Last year, growers who planted corn following soybeans in sandier soils reported Asiatic garden beetle grubs caused some stand losses, he said.
“Although this is a relatively new pest for corn growers, in heavily infested areas you could be looking at a 20 to 30 percent yield loss,” Michel said. “These grubs can lead to wilted and stunted corn and even the complete death of the plant.
“Asiatic grub feeding on corn can lead to gaps in the row with wilted plants that won’t contribute much to yield.”
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, which are a minor pest in the turf and ornamental industry, were recently associated as a corn pest in northeast Indiana and southwest Michigan from 2006 to 2008, always in sandier soils following soybeans.
“The epicenter of these grubs is northwest Ohio in the areas of the state with field crops grown in sandy soils,” Michel said. “We’re finding more fields with damage from Asiatic garden beetles and more growers are becoming aware of it.
“This pest is expanding in its range and moving into other pockets of the state where there are fields with sandy soils.“
Asiatic garden beetle grubs are smaller than other grubs such as true white grubs and Japanese beetle grubs. The main characteristics to identify Asiatic garden beetle grubs are the enlarged maxillary palps on the side of their mouthparts.
Growers statewide who have corn growing in sandy soils should start scouting for this pest, particularly paying attention to fields in river bottom areas where sandy soils are often found, Michel said.
“Look for corn stands in sandy soils that appear to have uneven growth stages, are wilting, or with gaps in the row,” he said. “Damaged fields often have gaps in rows, and affected corn often appears wilted and stressed.”
Growers should dig around the plant and look for the presence of white grubs, as demonstrated in this video from Michel.
But as with other grub problems, 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, Michel said.
“The only action would be replanting if necessary,” he said. “We anticipate the larva to pupate around mid-June, and by July, adult beetles will begin emerging to lay eggs all over again.”
Michel said there are some on-farm trials to see how these grubs can impact yield and to try to determine effective management tactics.
“We hope to have some more ideas of what may work or not work on Asiatic garden beetles by end of the year,” he said. “But at this time, there is no real silver bullet, no one management tactic that we know of yet that will give you real control.”