Renewable Farming

As weed resistance builds, total herbicide use keeps climbing

The total pounds of active herbicide applied in the U.S. accelerated from 2005 to 2011. That’s the latest detailed data available reported in a comprehensive study by researchers at four universities.

They include the University of Virginia, Iowa State University, Michigan State University, and Kansas State University.

The trendline projected on through 2016 indicates that farmers will soon be applying growing amounts of Roundup, plus as many pounds of non-glyphosate weedkillers as they did before Roundup came on the market.

The “pounds per acre” data probably understates the increase of herbicide trips required to combat resistant weeds, because many of the recently registered herbicides are labeled for just a few ounces per acre, not pints or quarts.  Here’s one of the charts from the study:

Pounds of herbicide active ingredients applied in the U.S.

You can download the entire PDF report at this link.



The study also includes data on pesticide usage. Bt technology has led to a decline in overall insect killers used, so far — probably because federal requirements call for refuge crops to delay onset of insect resistance.

The website Sustainable Pulse commented on the findings, noting that the study documents “massive environmental damage.” When GMO-linked weedkillers first arrived, they were promoted as leading to reduced chemical use.

Longtime friend Chuck Benbrook, who was a featured speaker at our “Renewable Farming” seminars several years ago, commented on the study as reported in Sustainable Pulse. We quote his message to Henry Rowlands of Sustainable Pulse:

“Their empirical findings re the impacts of GE crops on pesticide use in the US are close to mine, lending confidence in publicly available NASS data.  Their analysis stops at 2011, around the time herbicide use took off in response to the spread of glyphosate resistant weeds. The increase in pounds applied — the most common metric — since 2011 is real but modest, because many farmers have dropped a third glyphosate application at ~0.75 pound a.i. per acre, and replaced it with 2-3 actives, usually in a pre-mix, with a combined rate of around 0.2 +/- 0.1 pound of active ingredients.
“When measured by acre-treatments (number of distinct, single applications of any pesticide), the trends look very ominous for farmers, and the environment.”
Charles Benbrook,
Benbrook Consulting Services, 90063 Troy Road, Enterprise, Oregon 97828 Main: 541-828-7918