By KEVIN WALKER
Michigan Correspondent

PORTLAND, Ore. — Researchers at Michigan State University presented good news about soybean aphid research at this year’s IPM Symposium in Portland.

MSU agricultural economist Scott Swinton and doctoral student Feng Song gave a 20-minute presentation about the state of soybean aphid research and how integrated pest management (IPM) practices figure into the equation.

First of all, the good news: A paltry $17 million of federal and state funds earmarked for soybean aphid related research will yield $1.3 billion in economic benefits by 2017, or a return of 180 percent annually, the paper states. The bad news? The soybean aphid still exists in the United States and will continue to make production of soybeans more expensive.

The paper Swinton highlighted at the conference last March crunches these and other numbers, offering a wide-angle view as well as detailed figures. It also explains how producers are using IPM to get the most out of their soybean crop and how it saves everyone money in the process.

First of all, in this context IPM means checking whether there are enough pests to make spraying pay for itself. For soybean aphid, this “economic threshold” is 250 aphids per plant. During 2003-05, research by University of Minnesota entomologist David Ragsdale showed that when aphid levels exceed 250 per plant, spraying pays off. But lower aphid infestations won’t hurt yields enough to cover spray costs.

“The general idea is that it uses information about crop and pest biology to help growers make good decisions about treating their crops,” Swinton said. “Part of this research is about not wasting dollars on insecticides if you don’t need them.”

The $1.3 billion figure will hold true only if nothing else comes along to improve the situation further, Swinton said. He brought up the possibility that a genetically modified variety of soybeans might be brought onto the market.

“Introduction of new genetics might improve control of soybean aphids. If resistant varieties of soybeans come out it won’t be necessary to spray and the only reason to use IPM would be to prevent the aphids from developing resistance,” Swinton said.

The paper also provides a little bit of history on the soybean aphid. According to the paper, “(I)n China, where soybean aphid is native, soybean growers were observed to apply insecticide as many as four times in one season to avoid yield loss. In the United States, the insecticide treated soybean area in six (M)idwest states (Iowa, Illinois, Indiana, Minnesota, Michigan and Ohio) leaped to 20 percent in 2005, compared to less than 1 percent before 2000.”
Swinton cited USDA figures that 42 percent of soybean acreage was treated with insecticide in 2005; in Minnesota the figure was 30 percent in 2005, 56 percent in 2006; in Indiana the figure was 18 percent in 2005.