Herbicide use has increased more for non-GMO crops than genetically engineered varieties

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[Editor’s note: Andrew Kniss is a professor in the Department of Plant Sciences at the University of Wyoming.]

Herbicide use is among the most criticized aspects of modern farming, especially as it relates to genetically engineered (GE) crops. Many previous analyses have used flawed metrics to evaluate herbicide intensity and toxicity trends. Here, I show that herbicide use intensity increased over the last 25 years in maize, cotton, rice and wheat. Although GE crops have been previously implicated in increasing herbicide use, herbicide increases were more rapid in non-GE crops.

Even as herbicide use increased, chronic toxicity associated with herbicide use decreased in two out of six crops, while acute toxicity decreased in four out of six crops. In the final year for which data were available (2014 or 2015), glyphosate accounted for 26% of maize, 43% of soybean and 45% of cotton herbicide applications. However, due to relatively low chronic toxicity, glyphosate contributed only 0.1, 0.3 and 3.5% of the chronic toxicity hazard in those crops, respectively.

If left uncontrolled, weeds could reduce world food production by as much as 20–40%

[T]he increased use of herbicides may not be inherently bad, as sometimes these changes corresponded with lower toxicity.

The GLP aggregated and excerpted this blog/article to reflect the diversity of news, opinion, and analysis. Read full, original post: Long-term trends in the intensity and relative toxicity of herbicide use

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