November 26, 2003



Aphid Infestation Hurt US' Minnesota Soybean Industry

This season's soybean aphid infestation cost the United States' Minnesota farmers about $80 million and damaged nearly 4 million acres of crops, according to preliminary estimates by the University of Minnesota.

It's the first time growers statewide have been hit so hard by the pests. Experts say the insect, which sucks nutrients out of plants, threatens to reshape the state's $1.3 billion soybean industry.

What sets the soybean aphid apart from other corn and soybean insects is its ability to rapidly reproduce itself asexually - populations typically double in 2-3 days. One expert dubbed the battle against the tiny green insect "clone warfare."

For years, soybeans have been a consistently profitable crop and one with little risk. However it might be set for a change. Aphids increase costs dramatically because of spraying, and even that's no guarantee against yield loss.

After the state's first major outbreak of aphids in 2001, there was a slight dip in the number of acres of soybeans planted. After this year's inundation, many expect an even more dramatic drop from the 7.4 million acres in 2003.

Research suggests that farmers should start next season by budgeting for insecticide. If farmers hadn't sprayed about 40% of the state's soybeans, they would have faced up to $270 million in crop loss this year.

"Anytime a pest occurs, growers lose money," says Ken Ostlie, a professor and extension entomologist at the University of Minnesota. "It's a question of how little or how much they lose."

Experts believe the fast-producing aphid came from Asia to the United States and the bugs can be found in nearly every state surrounding the Great Lakes, continuing to spread farther out each year.

But Minnesota's climate and abundant soybean fields attract more aphids than other states.

They first appeared in a handful of Minnesota fields in 2000. In 2001, farmers in southeastern Minnesota dealt with an outbreak and sprayed about 50,000 acres.

This year, the problem exploded across the state. About 3 million acres were sprayed at a cost of $30 million, Ostlie said. Yield losses and reduction in quality account for the rest of the estimated $80 million loss.

Coupled with a two-month drought, soybean aphids reduced the number of bushels per acre to 31 - the lowest since 1993 - compared to 2002's record high of 43, according to the Minnesota Agricultural Statistics Service.

"I've never seen anything like this," says Bruce Potter, an integrated pest management specialist with the Extension Service in Lamberton. "Just the sheer magnitude of the problem, the sheer amount of yield loss, and the speed at which it happened. It was pretty incredible."

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