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HEALTH: Scientists Link GM Crop Weed Killer to Powerful Fungus

Jeremy Bigwood

WASHINGTON, Aug 20 2003 (IPS) - Scientists are expressing alarm after finding elevated amounts of potentially toxic fungal moulds in food crops sprayed with a common weed killer widely used with genetically engineered (GE) plants.

Roundup, produced by food-industry giant Monsanto, contains a chemical called glyphosate that researchers are blaming for increased amounts of fusarium head blight, a fungus of often very toxic moulds that occurs naturally in soils and occasionally invades crops, but is usually held in check by other microbes.

If true, the allegations could not only call into question the world’s number one weed killer, but they also jeopardise global acceptance of Monsanto’s flagship line of genetically engineered Roundup Ready crops.

Those crops are themselves unaffected by the Roundup weed killer, which kills all competing plants, such as weeds, in the same area.

Monsanto has been producing a series of GE Roundup Ready seed stock for various crops, including cotton, soybean, wheat and corn, to be used exclusively with their successful glyphosate weed killer Roundup. But because they are genetically engineered, the crops have not found easy acceptance in many countries outside the United States, and they are still banned in Canada and Europe.

A four-year study found that wheat treated with glyphosate appeared to have higher levels of fusarium than wheat fields where no glyphosate had been applied, said Myriam Fernandez of the Semiarid Prairie Agricultural Research Centre in Swift Current, in Canada’s Saskatchewan province.


"We have not finished analysing the four years of data yet or written up the study," she added in a recent interview with IPS.

While Fernandez’ research recently made headlines throughout Canada, it was not the first to discuss the relationship between glyphosate-containing weed killers and increased levels of potentially toxic fungi, but it was the first to report on the possibility of potentially toxic damage in wheat and barley, two of Canada’s most important crops.

A Monsanto spokesman was critical of the findings.

"It appears to be that Dr. Fernandez did a field survey looking at levels of Fusarium and then the factors that might be related," Harvey Glick, head of the company’s scientific affairs division, told IPS.

"So, from what I can gather, that was not a cause and effect. It’s just that they saw in the study area some fields that had higher levels of fusarium, for whatever reason, and then they looked at a list of factors that might be related and one of them was there was Roundup used in those fields the previous year."

Over the last two decades, several scientists from New Zealand to Africa have noticed and investigated the glyphosate-fusarium relationship through small-scale experiments in the relative obscurity of their labs and reported the results in academic journals.

The result of all of this work is almost 50 scientific papers, says Robert Kremer, a soil scientist at the University of Missouri. Overall, they describe an increase in fusarium or other microbes after the application of glyphosate.

Kremer’s ongoing research deals with the glyphosate-fusarium relationship on soybeans, including a Roundup Ready variety.

His experiments with Roundup Ready and regular soybeans revealed that glyphosate seems to stimulate fusarium in the plants’ roots, to such a degree that he considers the elevation of fusarium levels to be glyphosate’s secondary effect.

While Kremer found enhanced fusarium colonies in the roots of the plants, which could potentially reduce the harvest, he did not find them in the harvested soybeans themselves. But he said he still worries that fusarium could accumulate in the soil at such levels to produce an epidemic that would move from field to field throughout a wide area.

He also noted: ”We didn’t see enhancement of fusarium when other herbicides were used" without Roundup. But according to contracts, farmers planting Roundup Ready crops must use Roundup weed killer exclusively or in combination with other chemicals.

Monsanto’s Glick rejected Kremer’s suggestions. "Roundup is almost 30 years old, and scientists have been looking at all aspects of its use for at least that long. So there is a tremendous amount of information available."

"And that is why there is such a high level of confidence that the use of Roundup, based on all of this earlier work, does not have any negative impacts on soil microbes … And a lot of it has been published."

In a recent article titled ‘GM Cotton Blamed for Disease’, Australia’s ‘Farm Weekly’ predicted that up to 90 percent of the country’s cotton belt could be inundated by a fusarium epidemic within the next decade due to Roundup Ready cotton.

Fusarium contamination of cereals, such as the fusarium head blight (FHB) in wheat and barley that Fernandez is studying, has been responsible for serious crop losses.

About one-fifth of the wheat crop in Europe each year is lost to FHB, and in Michigan during 2002 it was estimated that 30-40 percent of crops were destroyed by the infestation.

When the mould passes into the food-chain undetected, fusarium epidemics on cereals can have even worse impacts: such an epidemic was considered responsible for thousands of deaths in Russia during the 1940s, and in 2001 it caused a series of deadly birth defects among tortilla-eating Mexican-Americans in Brownsville, Texas, after the blight infiltrated corn.

Minute amounts of fusarium continually enter commercial food products; it is at the higher levels that it can become a serious problem.

The fusarium fungus can produce a range of toxins that are not destroyed in the cooking process, such as vomitoxin, which as its name suggests, usually produces vomiting but not death. More lethal compounds include fumonisin, which can cause cancer and birth defects, and the very lethal chemical warfare agent fusariotoxin, more often referred to as T2 toxin.

During 2000, the U.S. Congress planned to use fusarium as a biological control agent to kill coca crops in Colombia and another fungus to kill opium poppies in Afghanistan.

Those plans were dropped by then-president Bill Clinton, who was concerned that the unilateral use of a biological agent would be perceived by the rest of the world as biological warfare.

Andean nations, including Colombia, banned its use throughout the region.

According to Sanho Tree, director of the drug policy project at the Washington-based Institute for Policy Studies, "the U.S. has supplied tens of thousands of gallons of Roundup to the Colombian government for use in aerial fumigation of coca crops."

That operation has "been using a fleet of crop dusters to dump unprecedented amounts of high-potency glyphosate over hundreds of thousands of acres in one of the most delicate and bio-diverse ecosystems in the world."

"This futile effort has done little to reduce the availability of cocaine on our streets, but now we are learning that a possible side-effect of this campaign could be the unleashing of a fusarium epidemic in the Amazon basin."

Because of the glyphosate-fusarium link, Canada’s National Farmers Union is already opposing Monsanto’s application to introduce GE Roundup Ready wheat into the country. The federal government is expected to make its decision within months.

 
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