There are thousands of ways to kill a weed. You can starve it, bleach it, mess with its proteins. You can feed it fake hormones. You can force it to make acid so that it disintegrates from within. There are more than 400 licensed weed killers, or herbicides, in Ontario alone. And we love to use them. Canadians used more than 58,000 tons in 2014, compared with only 21,000 tons in 1994. Our landscape, and our crops, have never been so saturated.
Our thirst for herbicides is partly due to GMOs like RoundupReady corn, soy, and canola. These herbicide-tolerant crops came on the market in the late 1990s, and changed the farming landscape by making it possible to control weeds by using herbicides on crops still in the field.
Herbicide resistance explains part of the increase in herbicide use around the world over the past decades. If you blast a weed with herbicide, eventually its cells become resistant. Farmers are left with fields of weeds they can’t kill. This is what happens in people, with antibiotic resistant bugs. Faced with resistant weeds, farmers double down, spraying even more and using multiple herbicides. But desiccation accounts for a significant part of the growth in herbicide use. It’s impossible to say precisely how much, because stats are tracked for herbicide use by crop—not by usage type.
In theory, anything that kills a plant can desiccate a crop, but farmers can only use herbicides that are licensed as desiccants. In practice, there are only a few that are regularly used.
Why spray—why spend the extra fuel and herbicide, if the crop is ready to go? “Insurance. When we spray we can harvest within 10 days.”
Glyphosate works by interrupting protein synthesis in plants, rendering them unable to photosynthesize. It is also considered relatively safe for humans. But in 2015 the World Health Organization (WHO) declared it a possible carcinogen, on the basis of an independent survey of the scientific literature. Outrage from governments and industry around the world fueled a reanalysis by the Food and Agriculture Organization of the United Nations and WHO, which concluded in 2016 that it was “unlikely to pose a carcinogenic risk to humans through diet.”
Industry, and farmers, breathed a sigh of relief. The reports analyzed, however, did not consider the increase in exposure to glyphosate via desiccation. This practice has dramatically increased the dissemination of glyphosate into the environment, and into us.
