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GMO corn: An organic farmer's best friend?

October 8, 2010 | 11:39 am

Cornborer It seems obvious that farmers who plant genetically modified crops designed to wipe out pests would see fewer nasty critters in their fields.

But new research shows that, at least in the case of one pesky insect in the U.S. Corn Belt, fields planted without the modified corn are enjoying its pest-killing benefits too.  Planting Bt corn — so called because it has been engineered to produce insecticidal proteins from a bacterium called Bacillus thuringiensis -- pushes numbers of the European corn borer so low that non-Bt cornfields are also losing less corn to the critters.

That could be great news for farmers supplying corn for organic dairy farms, said study co-author Paul Mitchell, an agricultural economist at the University of Wisconsin in Madison.

Mitchell crunched the numbers and discovered that using GMO corn to wipe out the borers has saved farmers in Minnesota, Illinois, Wisconsin, Iowa and Nebraska $6.9 billion over 14 years. About two-thirds of the savings came from fields planted with non-Bt corn -- where farmers save more because they're not paying for the more expensive, genetically engineered seeds.

The GMO fields depend on nearby non-GMO fields, known as refuges, to help prevent the corn borers from developing immunities to the insecticidal toxins generated by Bt corn. This research, published Thursday in the journal Science, could encourage farmers to plant more, not less, non-engineered corn.

Until 2008, farmers planting Bt corn were required by the Environmental Protection Agency to reserve at least 20% of their fields for non-Bt plants. Scientists hypothesized — correctly, it now appears — that such non-Bt "refuges" would help stave off Bt resistance among corn borers. 

But some farmers reportedly resisted the rules, planting more than 80% of their crops with Bt corn to make sure they didn't lose a portion of the crop to the borer. The new research suggests that farmers have nothing to fear from planting non-Bt refuges alongside Bt fields. They may make more money by doing so. 

In fact, farmers may stand to gain by planting even more non-Bt corn than the EPA requires, scientists said. Lead author William Hutchison, an entomologist at the University of Minnesota, said that if he were a farmer, he thought he might use a 60% Bt, 40% non-Bt mix, or even a 50-50 combination.

But Margaret Mellon, director of the food and environment program at the Union of Concerned Scientists, which advises a cautious approach to genetically modified crops, wondered whether the savings attributed to Bt corn was enough to merit fanfare. By her estimates, the savings ran to only about 3% of the total value of the corn crop in the five states. "The benefits are real, but they're modest," she said.

Genetically modified crops have been the subject of furious controversy in Europe, where they have prompted government restrictions, and among U.S. environmentalists and organic farmers.

Read more about the GMO corn study and the European corn borer.

-- Eryn Brown

RELATED:

Genetically modified crops pop up in the wild

Genetically engineered salmon: ban it or label it

Seed-maker Monsanto posts loss amid competition, criticism

Photo: European corn borer larvae chomp through fields in the U.S. Corn Belt, causing an estimated $1 billion in losses each year. Credit: Science /AAAS

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