Integrated Crop Management

Iowa State forms the aphid team and shares research results

Faculty and staff from Iowa State University (ISU) Extension, the ISU Department of Entomology, and the Iowa Soybean Association have formed the Iowa Soybean Aphid Task Force.

"The Task Force's intent is to proactively plan soybean aphid management strategies. The Task Force is collecting and synthesizing the latest research information and preparing it for rapid delivery through the Web page, publications, and grower meetings," says Jon Tollefson, the Task Force leader and chair of the Department of Entomology.

"Iowa soybean producers are the biggest beneficiaries of the work this team is doing," said David Wright, Director of Production Technology, Iowa Soybean Association and Task Force member.

"Early observations of overwintering sites and early-planted soybean fields suggest aphid numbers could be very high this year," he continues. "This team will ensure soybean producers are well informed of the presence of aphids and cost-effective management techniques through diligent statewide monitoring and constant communication with producers."

If aphids do become a pest this season, producers may want to tank mix insecticides with postemergence herbicides to reduce the number of trips to the field. An ISU entomologist has done research in this area and says the practice has some drawbacks.

Large colony of soybean aphids [1]
A large colony of soybean aphids often includes white, shed skins and brownish carcasses killed by fungal pathogens. (Marlin E. Rice)

In 2004, Matt O'Neal, assistant professor of entomology, investigated how tank mixing insecticides with herbicides affects soybean aphid control. He did research where plots with high aphid populations (more than 250 aphids per plant) were treated with insecticides either applied normally or through nozzles at pressures used for applying postemergence herbicides.

"Applying insecticides as one would a herbicide reduces the ability of the insecticide to kill aphids. By reducing the risk of herbicide drift, growers are not applying the insecticide with the coverage it requires. Our data from 2004 suggest that this reduced coverage allows aphids to survive after the insecticide has been applied."

A more complete report on this research can be found at the Iowa Soybean Aphid Task Force Web address,

O'Neal is continuing the research in the 2005 crop season. ISU researchers are also working on other methods of managing soybean aphids. Those include:

The Task Force plans regular communication this summer to producers through ISU newsletters, the Web, and through the news media.

This article originally appeared on page Page 1 of the IC-494(14) -- June 13, 2005 issue.

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