(Page 2 of 5)
2. GMOs Increase Herbicide Use
First, so what? This claim is simply an attempt to mislead people into thinking that more herbicide use must somehow be more dangerous. As a U.S. Department of Agriculture report has noted, planting herbicide resistant biotech crops enables farmers to substitute the more environmentally benign herbicide glyphosate (commercially sold as Round Up) for “other synthetic herbicides that are at least 3 times as toxic and that persist in the environment nearly twice as long as glyphosate.” Glyphosate has very low toxicity, breaks down quickly in the environment, and enables farmers to practice conservation tillage, which reduces topsoil erosion by up to 90 percent. So the net environmental effect is still positive.
Second, it must be admitted that there are few honest brokers when it comes to this issue. Most of the research on biotech crops and herbicides is underwritten by either activist groups or industry. I have drawn my own conclusions, but I provide a fairly comprehensive review of the various studies on this question below.
When it comes to biotech crops and pesticide use data, the go-to guy for anti-biotech activists is Charles Benbrook. After a long career with various anti-biotech groups, Benbrook now serves as a research professor in the Center for Sustaining Agriculture and Natural Resources at Washington State University. He has a long history of publishing studies allegedly showing that the adoption of biotech crops boosts the use of pesticides. Four years after commercial biotech crops were first planted in the United States, for example, he concluded in 2001 that herbicide use had “modestly increased.” Benbrook’s article contradicted research published the year before by scientists with the U.S. Department of Agriculture, who had found that biotech crops had reduced pesticide applications.
In a 2004 report funded by the Union of Concerned Scientists, Benbrook asserted that “GE [genetically engineered] corn, soybeans, and cotton have led to a 122 million pound increase in pesticide use since 1996.” In contrast, a 2005 study in Pest Management Science, by a researcher associated with the pesticide lobby group CropLife, reported that planting biotech crops had “reduced herbicide use by 37.5million lbs.” A 2007 study done for the self-described non-advocacy think tank National Center for Food and Agricultural Policy, founded in 1984 by the W.K. Kellogg Foundation, reported that planting biotech crops in the U.S. had reduced in 2005 herbicide use by 64 million pounds and insecticide applications by about 4 million pounds. Another 2007 study, by a team of international academic researchers led by Gijs Kleter from the Institute of Food Safety at Wageningen University in the Netherlands, concluded that in the U.S., crops genetically improved to resist herbicides used 25 to 30 percent less herbicides than conventional crops did. In 2009, Benbrook issued a report for the anti-GMO Organic Center claiming that “GE crops have been responsible for an increase of 383 million pounds of herbicide use in the U.S. over the first 13 years of commercial use of GE crops.”
Benbrook’s latest study, issued last year, found that the adoption of pest-resistant crops had reduced the application of insecticides by 123 million pounds since 1996 but increased the application of herbicides by 527 million pounds, an overall increase of about 404 million pounds of pesticides. The media—including Mother Jones’ ever-credulous anti-biotech advocate Tom Philpott— reported these results unskeptically.
Benbrook largely got his 2012 results by making some strategic extrapolations of herbicide use trends to make up for missing data from the U.S. Department of Agriculture. In fact, the USDA does not provide herbicide use data for corn in 2004, 2006, 2007, 2008, 2009, or 2011, for soybeans in any year after 2006, and for cotton in 2002, 2004, 2006, 2009, and 2011. (The USDA’s National Agricultural Statistics Service is expected to issue a report updating national herbicide and insecticide usage later this year.)
As the University of Wyoming weed biologist Andrew Kniss points out, in order to get an increasing herbicide trend, Benbrook’s extrapolations turned a negative herbicide use trend for corn positive. He did the same thing to a neutral use trend for soybeans. Meanwhile, a 2012 study by Graham Brookes and Peter Barfoot at the PG Economics consultancy found planting modern biotech crop varieties had globally cut pesticide spraying by 997 million pounds from 1996 to 2010, an overall reduction of 9.1 percent. Brookes and Barfoot calculated the amount of pesticide used by multiplying the acreage planted for each variety by the average amounts applied per acre.