Soybean-damaging bugs known for their “sweaty feet” smell when squashed or irritated have made their way into Ohio soybean fields in numbers not previously experienced in the Buckeye State, an Ohio State University Extension entomologist said.
Growers are being advised to be on the lookout for the brown marmorated stink bug, said Ron Hammond, who also has an appointment with the Ohio Agricultural Research and Development Center.
A native of eastern Asia, the brown marmorated stink bug was first identified in the U.S. in Allentown, Pa., in 2001. The brown, three-quarter-inch bugs are known to feed on a wide range of crops, including apples, peaches, tomatoes and soybeans.
Sightings of larger-than-usual numbers of green stink bugs also have been reported in Ohio soybean fields, as well as red shouldered stink bugs, which are a newer pest in Ohio, Hammond said.
“This is the first year we are seeing this amount of green stink bugs in Ohio, as they are typically more prevalent in southern areas,” he said. “With the warmer temperatures experienced over the past decade, we predicted that we would see more stink bugs in the north than normal.”
The concern for soybean growers is the potential for yield declines as a result of stink bugs, which use their piercing-sucking mouthparts to feed on the plant seeds.
“They cause direct damage to the seed,” Hammond said. “It doesn’t take a lot of stink bugs to cause an economic loss. Growers need to be aware of this, especially for food grade (soybeans) and soybeans grown for seed.”
Hammond advised growers to sample their fields for the smelly pests by taking multiple, 10-sweep samples with a sweep net in multiple locations throughout the field. Then, they should average the number of stink bugs in the 10-sweep samples.
“The threshold to treat is four or more stink bugs, adults or nymphs,” Hammond said. “If soybeans are food-grade soybeans or being grown for seed, the threshold can be dropped to two or more stink bugs.”
“Some fields in Ohio have already met that criterion.”
Because stink bugs often occur mainly on the field edges, especially next to woody areas, growers should sample both the field edge and within the field to determine which parts of the field may require treatment, he said.
“If treatment is required, most insecticides registered on soybean have stink bugs on their label,” Hammond said. “However, at this time of year, growers should make note of the pre-harvest intervals, as many insecticides probably can no longer be used because of the short time before harvest.”