Organic Consumers Association

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Acres USA Interviews Don Huber on Dangers of Monsanto's Roundup-Ready Crops

ACRES U.S.A. How does glyphosate differ from herbicides that were popular before it came along?

DON HUBER. There are a number of ways that glyphosate is different from most other herbicides. Most of our herbicides are mineral chelators that act to physiologically immobilize a specific mineral nutrient that is required for a specific critical enzyme. When that physiological pathway is shut down, the weed or the plant it's applied to dies. Glyphosate also is a chemical chelator that can grab onto mineral nutrients and immobilize them physiologically so they're no longer available for those physiologic functions that they regulate. The difference with glyphosate is that it is not specific to just one mineral nutrient, but immobilizes many of them and doesn't affect a primary mechanism to cause death by itself. It merely turns off the plant's defense mechanisms so that soil-borne fungi that would normally take weeks to months to damage a plant can kill it in just a few days after glyphosate is applied. When they use the glyphosate-tolerant technology, they insert another gene that keeps that plant's defense mechanism going somewhat so you can put the glyphosate directly on the crop plant without having it killed. But the technology doesn't do anything to the glyphosate, which is still tying up mineral nutrients. Anytime you put the gene in, you reduce the nutrient efficiency of the plant, though not to the point that it destroys the ability of the plant to survive. It does leave it physiologically impaired.

ACRES U.S.A. Before glyphosate-tolerant genes were introduced, how did farmers cope with the danger of possibly killing the crop plant?

HUBER. They took care of their weed control before planting or before the crop emerged. Back then, there weren't too many herbicides that you could apply directly to the plant. We had a few, 2,4-D and a few others, that were semi-selective and very effective against broadleaves, which have a different physiology than grass plants. A similar thing with Tordon. You can put Tordon right on a grass pasture and it will kill the broadleaf weeds for three or four years. It has pretty good residual activity, but grass looks like you'd just fertilized it when you got rid of all of those broadleaved weeds.

ACRES U.S.A. The innovation that gave glyphosate its market clout had to do with concentrating the whole arsenal into one weapon? No more multiple herbicides?

HUBER. There was selective activity in our herbicides. Glyphosate on plants without the new gene inserted has a very broad-spectrum effect so that all weeds are affected. They're all killed by the soil fungi. It's not quite analogous, but you could say that what you're doing with glyphosate is you're giving the plant a bad case of AIDS. You've shut down the immune system or the defense system.

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