Robert Kremer is a microbiologist with the US Department of Agriculture’s Agricultural Research Service and an adjunct professor in the Division of Plant Sciences at the University of Missouri. He is co-author of one of five papers published in the October 2009 issue of The European Journal of Agronomy that found negative impacts of Roundup herbicide, which is used extensively with Roundup Ready genetically modified crops. Kremer has been studying the impacts of glyphosate, the primary ingredient in Monsanto’s Roundup herbicide, since 1997.

The Organic & Non-GMO Report interviewed Mr. Kremer about his research and the reluctance of the USDA to publicize the findings of the five papers.

Please give me an overview of your research.

RK: We started in 1997 wanting to see if this new system, Roundup Ready, would change the production of nematodes in soybean. We started looking at organisms in soybean roots and saw microorganisms colonizing the roots. We suspected that glyphosate was having an impact. There was a root fungi problem that seemed to be encouraging sudden death syndrome (SDS). We saw the increase of these fungi in the Roundup Ready (genetically modified) system, both soybeans and corn.

What types of things are you seeing in the Roundup Ready system?

RK: This system is altering the whole soil biology. We are seeing differences in bacteria in plant roots and changes in nutrient availability. Glyphosate is very systemic in the plant and is being released through the roots into the soil. Many studies show that glyphosate can have toxic effects on microorganisms and can stimulate them to germinate spores and colonize root systems. Other researchers are showing that glyphosate can immobilize manganese, an essential plant micronutrient.

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What are glyphosate’s impacts on beneficial soil bacteria?

RK: The most obvious impact is on rhizobia, a bacterium that fixes nitrogen. It has been shown that glyphosate can be toxic to rhizobia. (Nitrogen fixing bacteria are important to soils because nitrogen is the most commonly deficient nutrient in many soils.)

What about research showing increased incidence of Fusarium in Roundup Ready GM crops?RK: We’ve taken field surveys and seen an increase in Fusarium with the use of glyphosate. Some Roundup Ready varieties even without using glyphosate tend to be more susceptible to being impacted by Fusarium. It could be an unintended consequence of genetic manipulation that could make it more susceptible.