New threats to farmers as weeds and bugs adapt

New genetically-modified seeds hope to target resistance

By JOSEPHINE MARCOTTY Minneapolis Star Tribune Published:

Danny Serfling knew he was in trouble in July. Tiny white worms in the soil had eaten away the anchoring roots on half of his corn, and in one big storm last summer, the stalks toppled like sticks.

"All the corn around here went flat," said Serfling, who farms a few hundred acres in southeastern Minnesota. He waved a tattooed arm toward stubbled hills that rolled away to the gray sky, resigned to the next step. "We will have to use more insecticide," he said.

It is what scientists and environmentalists regard as one of nature's great ironies: Fifteen years ago, genetically engineered seeds promised to reduce the amount of poisons used on the land, but today they are forcing farmers to use more -- and sometimes more toxic -- chemicals to protect their crops.

Why? Because pests have done what nature always does -- adapt. Just as some bacteria have become resistant to antibiotic drugs, a growing number of superweeds and superbugs are proving invulnerable to the tons of pesticides that go hand in hand with genetically modified seeds.

The rising tide of pesticides is alarming scientists and environmentalists about their effect on what's left of the North American prairie ecosystem, which survives in and around the vast "green deserts" of row crops that stretch across the Upper Midwest.

"There are now 80 million acres of treated corn," said Eric Mader, an ecologist with the Xerces Society for Invertebrate Conservation. "That's a huge volume of pesticides applied for one crop."

To combat the growing wave of resistant weeds and bugs, Monsanto and Dow Chemical Co. are poised to launch a new arsenal of genetically modified seeds that will accelerate the chemical warfare. Some are designed for use with older, more toxic herbicides that scientists say pose an even greater risk to the environment and human health.

The biotech companies say they will educate farmers and extension agents on how to minimize the health and environmental risks, and that the multiple genetic weapons contained in the new seeds will make it impossible for pests to develop resistance.

"We believe this can be managed," said Rick Cole, a weed management technical lead for Monsanto.

Still, a rising chorus of protest from environmental and agricultural scientists says it won't work. Nature, they say, will simply adapt again.

"It makes about as much sense as pouring gas on a fire to put it out," said Charles Benbrook, a researcher at Washington State University. "It is going to lead to the exact same problem and a substantial increase in much less benign herbicides."

Fifteen years ago, genetically modified seeds revolutionized farming.

Monsanto introduced the first, a variety of soybean that was immune to the herbicide Roundup. Suddenly, life got a lot easier for farmers. They could spray their fields once or twice with Roundup -- prized because it kills virtually all plants but is largely benign to animals and people -- and then plant their crops. And they no longer had to till the land to get rid of pesky weeds, greatly reducing the potential for soil erosion.

Roundup-ready cotton, corn, canola, alfalfa and sugar beets followed in quick succession, making Roundup one of the most widely used herbicides in the world. "Farmers were very quick to adopt it," said Cole.

A few years later, Monsanto introduced the next genetic advance -- corn that contained its own insecticide, a protein called Bt that is poisonous to insects. Bt corn also was viewed as an environmental boon, because it was highly targeted -- it killed only the insects that ate the corn. That meant far less aerial spraying and dousing soils with poisons that killed everything from worms to birds.

And it worked. The U.S. Department of Agriculture reported that per-acre use of pesticides on corn, soybeans and cotton declined by several million pounds per year, and soil tillage declined, as well.

But the genetic breakthroughs brought sweeping changes across the landscape. Today, much of the Midwest is planted with just two genetically modified species -- corn and soybeans.

In short, Midwestern agriculture quickly evolved into a vast, efficient system that is much easier to farm but is "biologically simple," said Doug Gurian-Sherman, a senior scientist with the Union of Concerned Scientists, and a specialist on biotech agriculture.

"The problem is," he added, "it's a perfect storm for resistance."

Adaptation is as old as evolution itself. First, the few weeds or bugs that just happen to be immune to the pesticide survive. Then, in a biologically simple environment devoid of competition or threats, they flourish. Farmers encountered pesticide resistance many times before Roundup and genetically modified crops came along.

But the revolution in agriculture has become a victim of its own success.

In recent years, scientists have identified an estimated 23 weeds around the world that no longer die when doused with Roundup. Many are the most prolific and two, giant ragweed and water hemp, are a bane to farmers. "The scale of it is really dramatically different," said Gurian-Sherman.

More recently, infestations of rootworm, known as the $1 billion insect because of its cost to farmers, have exploded.

The next generation of genetically modified seeds, designed to combat the new resistant pests, will work for a while, skeptics concede. But eventually, they say, nature will evolve again.

"My jaded, cynical perception is that it indicates a learning disability on the part of everyone," said Bruce Potter, an assistant professor of entomology at the University of Minnesota.

There is another solution, says Potter, but one that can work against the economic interests of farmers and pesticide companies: Plant something else for a while. Alternating corn and soybeans, and mixing in other crops from season to season, can improve the soil and defeat the bugs and weeds.

It's a lesson in leveraging biological diversity that Serfling saw with his own eyes. This summer he had to hire a helicopter to spray insecticide on his bug-infested corn. But across the driveway, another field stood tall in the wind. The difference: The previous year, he'd planted alfalfa.

"Rotate. That's how you get rid of it," he said. "Rotate, rotate, rotate."

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