Reports from Extension field crop specialists on June 28 revealed that the soybean aphid populations are consistently small, or nonexistent, in many fields and the insect is not a significant problem anywhere in Iowa. Paul Kassel, Extension field crop specialist, reported that a crop consultant had found soybean aphids in Buena Vista County, but again this was a small population. Matt O'Neal, assistant professor of Entomology, noted that the soybean aphids in his research plots in Ames were slowly increasing and had spread to about a half dozen plants in two rows. He also noted that the aphid colonies were producing winged aphids, which means that the aphids will be moving to infest other plants or fields.
There has been some spraying of fields across eastern and southern Iowa but most indications are that these fields were not at the economic threshold of 250 aphids per plant. Scouting for soybean aphids should begin in early July and continue weekly through early August. More information will be presented next week on scouting guidelines.
This article originally appeared on page 82 of the IC-492(14) -- July 5, 2004 issue.