The soybean aphid has arrived in Ohio. Ohio State University Extension entomologists have found the sapsucker on early planted soybeans, and in some fields at numbers higher than expected.

Ron Hammond, an OSU Extension entomologist with the Ohio Agricultural Research and Development Center (OARDC), says that the find is following this year's prediction of high soybean aphid populations. He is encouraging soybean growers to get out in their fields and start scouting.

"We knew that parts of Michigan, Indiana and areas in Canada, such as Ontario and Quebec, had found aphids. We were out in the fields in northwest Ohio last week and found a few, so that meant that aphids had survived overwintering," says Hammond. "But just this week, we scouted early planted fields at OARDC and, to our surprise, we were finding aphids, and not just one or two. Many plants had 30-50 aphids on them; some had over 100 aphids. Based on this assessment, the soybean aphid has the potential to be a huge economic problem we expect in these odd-numbered years."

The soybean aphid, first discovered in Ohio in 2001, is a sapsucker whose voracious appetite can greatly damage untreated soybean fields. It also has been known to transmit a host of viruses, including soybean mosaic virus, soybean dwarf virus and alfalfa mosaic virus, not only in soybeans but also in a number of vegetable crops.

Finding soybean aphids in a high-population year is expected, but what is unusual this year is the large number of aphids being found so early in the season. The situation, says Hammond, could be that many soybean fields were planted late this year due to persistent wet weather, so early planted fields are receiving the brunt of aphid colonization.

"It's not a normal situation for these early plants to have these kinds of numbers in Ohio, but when the soybean aphid began its initial movement after overwintering, early planted fields were the only soybean plants available. So we are seeing heavier infestations than normal," says Hammond. "In a normal year with more soybean plants in the ground, the aphids might have spread themselves across fields and the insects wouldn't have been so concentrated or as high in one area."

Hammond recommends that growers with early planted fields scout their plants for any abnormal soybean aphid buildup. This recommendation especially holds true for soybeans not treated with an insecticide seed treatment, such as Cruiser.

"Right now, we think the chances of growers finding aphids on most soybeans are slim because of the late planting. However, if they have early planted fields, it would be worthwhile to scout," says Hammond. "We have not been finding aphids on fields treated with Cruiser."

Specialists will be keeping a close watch on soybean aphid populations throughout the summer. Hammond cautions that what actions growers take now may or may not have any impact on potential soybean aphid population explosions come July.

For growers, the best way to manage the soybean aphid is to educate themselves on the insect, know when to scout and to carefully time foliar insecticide applications if treatments are warranted. The economic threshold of aphids is 250 insects/plant with a rising population.

"We continue to recommend taking an integrated pest management (IPM) approach to aphid management. While seed treatments will control early season aphid populations, they will not have any impact in mid-summer when aphids arrive in large numbers," says Hammond. "We will recommend scouting soybeans from early July through August, and using the threshold with a rising population density to determine the need for treatment."

Information on soybean aphid infestations throughout the Midwest can be found on the North Central Regional Soybean Aphid Suction Trap Network. For further updates on the soybean aphid and its impact on Ohio's soybean crop, refer to the OSU Extension's Agronomic Crops Team, or the new Agronomic Crops Insects Web site.