If indications from fall trappings in the Midwest are proven correct, growers may see minimal soybean aphid pressure this growing season, according to a news release from Pioneer Hi-Bred.
"Soybean aphids tend to be more prominent during odd years," says Leon Streit, Pioneer senior research scientist. "However, although we are in an even-year growing season, Pioneer suggests growers continue to monitor fields regularly. There still may be areas that have a spike in soybean aphids."
Soybean aphids migrate in the fall to buckthorn, the overwintering host. According to the U.S. Department of Agriculture integrated pest management website, suction traps in fall 2007 recorded low numbers of winged soybean aphids migrating. This indicates a year of low pressure.
While soybean aphid pressure may prove minimal this year, Pioneer suggests growers continue to scout fields for any indication of the pest. Aphids are small and yellow with distinct black cornicles ("tailpipes"). At only one-sixteenth inch long (the size of a pinhead or smaller), they cannot be distinguished from other aphids with the naked eye. It is the only aphid in North America known to extensively colonize in soybean fields.
"Aphids have natural enemies that help reduce populations," says John Soper, senior research director for Pioneer. "However, if a grower has 250 aphids per soybean plant, an insecticide treatment is recommended."
To aid in monitoring this pest, a number of state university websites and the USDA track the movement of aphids. Growers can monitor sites such as www.sbrusa.net (select soybean aphid in the upper right-hand corner drop-down menu) and begin scouting when aphids appear in their area.