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Nebraska research safeguards sustainable world crop yields

By Alex and Dennis Avery
web posted July 2, 2007

The journal Science editorialized on May 23rd that the world is becoming too dependent on Roundup-Ready biotech crops. It claimed agriculture had become as dependent on glyphosate for weed control as human medicine had become on antibiotics. The journal predicted: "There is going to be an epidemic of glyphosate-resistant weeds."

In the very same issue, however, the University of Nebraska reported that it has developed crop tolerance for the herbicide dicamba, adding a new genetically engineered weed control option to our arsenal. This will permit continued expansion of sustainable, low-erosion, high-yield farming during the next 40 years of surging world crop demand.

"We can now spray dicamba [a phenoxy herbicide] on a number of different [crop] plants and have no visible symptoms at all," says Nebraska molecular biologist Donald Weeks. He found that dicamba-resistant soybeans could withstand five times the typical field application of the herbicide. Dicamba features a low toxicity—about one-third as high in mice as the organic pesticide pyrethrum—and low soil persistence.

Giving up herbicides and low-till would lead to more soil erosion, driving lower yields and eventually ruining much of the world's cropland. Conservation tillage has cut soil erosion in crop fields by up to 90 percent through low-till and no-till farming. Both use herbicides to kill weeds, rather than relying on traditional plowing. Organic, which bans low till, is not a solution. It takes nearly twice as much land to produce a ton of food because the fields must produce their own nitrogen as well as the food.

Until now, only the tolerance for the Roundup has been bioengineered into crop plants. Roundup kills all weed types, and that's a big reason why glyphosate-tolerant crops are now being planted on more then 220 million acres per year, worldwide. They've been the fastest-spreading farm technology in history.

Nebraska's new dicamba resistance effectively ends the mini-panic over glyphosate, however. Now, the industry has two effective all-weed herbicides that can be bred into crops and rotated—or even stacked in the same seeds—to prevent any major resistance. In addition, farmers can also utilize Bayer's Liberty-Link, a non-biotech breeding intervention that relies on gluphosinate and a different mode of action than glyphosate. There are also sprayed-on weed killers such as atrazine, which offer low costs and low environmental impacts, but without the reduced pesticide sprayings of the herbicide-tolerant plants.

Even more important, Nebraska's success in finding a disarming gene for dicamba raises hopes that other disarming genes can be found to provide tolerance for still more herbicides, thanks to the world's genetic diversity.

Dicamba tolerance is also a body blow to activist claims that genetically engineered crops should be banned. Weeks' creation works through the plants' chloroplasts, which means the modified crops can't spread resistance through pollen carried by wind or insects. Over time, this will even disarm the activist claim that biotech crops threaten the plantings of nearby organic farmers.

It looks like biotech crops will be with us for the long haul—helping humanity feed a peak human population of perhaps 9 billion people without taking more cropland away from nature. ESR

Dennis T. Avery is a senior fellow for Hudson Institute in Washington, D.C. and is the Director for Center for Global Food Issues. He was formerly a senior analyst for the Department of State. Alex A. Avery is the Director of Research at the Hudson Institute's Center for Global Food Issues. Readers may write them at Post Office Box 202, Churchville, VA 24421.


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