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College of Food, Agricultural, and Environmental Sciences


Timing of Soybean Rust May Impact Soybean Aphid Control

January 27, 2005

WOOSTER, Ohio — Soybean growers are bracing for a soybean aphid population explosion this growing season, and controlling the pest could become even more challenging if soybean rust is thrown into the mix of management practices.

Ron Hammond, an Ohio State University research entomologist with the Ohio Agricultural Research and Development Center, said that whether growers can control the soybean aphid and soybean rust at the same time will depend on whether or not soybean rust shows up at all and if so, at what time during the growing season.

"Timing is going to be everything if it boils down to growers having to management both the aphid and rust," said Hammond. "If rust were to show up early in the growing season, it's probably not a good idea to spray for the aphids at that time. If you spray too early before thresholds, you could have a bigger population on your hands later on. However, if rust shows up later in the season, a grower might be able to apply an insecticide and fungicide together."

How to manage the soybean aphid in the face of a possible soybean rust appearance is just one pest management tip Hammond will be offering to growers at the Conservation Tillage and Technology Conference Feb. 24-25 at Ohio Northern University in Ada, Ohio.

"We don't know what's going to happen if soybean rust was to show up, but we do know this. We are expecting the aphid this year, so growers should be out in their fields scouting come mid-to-late July," said Hammond. "And take the necessary steps to spray for the pest if it reaches the threshold of 250 aphids per plant. It costs the equivalent of three bushels to spray a field. A grower can easily lose that with a good soybean aphid population."

Hammond also recommended that growers think of ways of entering their fields to spray without damaging the soybean crop.

"We recommend growers consider skip rows or tram lines. This production practice causes miniscule yield losses when spraying for rust or aphids because a grower is not running over his beans," said Hammond. "In August, if you run down those plants, you've completely lost them."

A seed treatment, called Cruiser, has been recently registered for soybean aphid treatment. But questions remain as to the effectiveness of such a product for a pest that doesn't appear until late in the growing season. "The larger a plant gets and longer it is in the field, the more diluted seed treatments become in the plant," said Hammond. "We are currently testing the product and at this time we are still recommending an IPM approach to managing the soybean aphid, that is, scout and spray at threshold ."

In addition to soybean aphid discussions at the conference, Hammond will also address two new products that will be available for slug control. Both products are expected to cost cheaper than the bait currently on the market.

The Conservation Tillage and Technology Conference is sponsored by Ohio State University Extension, Northwest Ohio Soil and Water Conservation Districts, USDA Natural Resources Conservation Service, USDA Farm Service Agency and the Ohio No-Till Council.

For more information, call the Allen County Soil and Water Conservation Districts at (419) 223-0040 or Ohio State Extension Hancock County office at (419) 422-3851.

Candace Pollock
Ron Hammond