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College of Food, Agricultural, and Environmental Sciences


High Soybean Aphid Populations Predicted in Ohio

April 8, 2009

WOOSTER, Ohio -- High soybean aphid populations are predicted for this growing season in Ohio, continuing the trend of low populations one year and high populations the next, according to Ohio State University Extension entomologists.


The prediction is based on information collected last fall in neighboring states.

"The main criteria we are basing this on are the fall collections of winged aphids in suction traps in neighboring states to our west and north. In a number of these traps, fall collections were high," said Ron Hammond, an OSU Extension entomologist based at the Ohio Agricultural Research and Development Center. "These numbers had followed a summer when suction trap collections in these same sites were very low. This scenario, low summer captures followed by high fall collections, has usually been the determining factor when making the aphid prediction for Ohio."

Information on the North Central Regional Soybean Aphid Suction Trap Network can be found at

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 soybean but also in a number of vegetable crops.

The only caveat to this year's prediction is that entomologists did not find any aphid colonies or eggs on the few buckthorn plants that were sampled in the fall in Ohio. Buckthorn is an overwinter host for the aphid.

"Because most of our aphid problems migrate from the north, we do not think that the lack of overwintering aphids in our state should be a determining factor. As always, we could be wrong in our prediction, but we have called it correctly for the past six out of seven years," said Hammond. "On the plus side, if we are wrong, at least it will be to the grower's benefit."

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 per plant.

"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. Thus, we do not recommend seed treatment insecticides for aphid control," said Hammond. "What we do recommend is scouting soybeans from early July through August, and using the threshold with a rising population density to determine the need for treatment."

For further updates on the soybean aphid, refer to the OSU Extension's Agronomic Crops Team Web site at


Candace Pollock
Ron Hammond