It’s time to curtail pre-harvest glyphosate

Glyphosate is under siege nationally and internationally. Stopping its pre-harvest use might be a logical step to quell the uprising and preserve the world’s most popular herbicide for other applications.

This wouldn’t stop activists from railing against what they view as an evil cancer-causing poison, but it would go a long way to addressing the issue of glyphosate residues in food.

The general public doesn’t understand and probably can’t be made to understand the concept of maximum residue limits. For them, any level of weed killer in their bagel, doughnut or hummus is too much. It just shouldn’t be there.

It doesn’t matter if it’s a part per million, per billion or per trillion. It doesn’t matter if the level is one-tenth what’s deemed as acceptable and safe. It’s hard to argue with a general population that’s scientifically illiterate.

The vast majority of the measurable glyphosate in harvested crops is the result of pre-harvest applications. Glyphosate used as a weed burn-off before seeding shouldn’t be an issue, and early season application to glyphosate-resistant crops should not be a source of measurable residue, either.

It’s the application leading up to harvest that causes measurable residues. Producers are being told not to apply until crops are below 30 percent moisture, but not everybody follows that advice. As well, maturity can be highly variable across a field.

Officially, glyphosate is not considered a desiccant. Pre-harvest use is supposed to be for the control of perennial weeds, not for crop dry down. However, not every producer views it that way. Frankly, glyphosate is over-used and carelessly applied all too often because it’s comparatively cheap.

Back in the 1970s and 1980s, Roundup was $24 a litre and was only cost effective for spot applications. If you’re old enough, you may remember Focus on Inputs, led by Ken Goudy of Melfort, Sask., which tried to establish a generic Roundup manufacturing facility. Those were the days before Roundup Ready canola.

It was Goudy who first told me about the potential to use glyphosate pre-harvest, saying this use was common in Europe. At the time, it seemed strange to be spraying a weed killer on a crop not long before putting it in the bin.

When Roundup came off patent and generic manufacturing drove the price down, use skyrocketed. For farmers, the main worry has been the rise of glyphosate-resistant weeds. Now we should be worried about losing the chemistry altogether.

The international report labelling glyphosate as a probable carcinogen has been widely discredited, but the damage has been done.

We will see more and more food companies stipulating that they don’t want grain in which glyphosate has been applied pre-harvest. Unfortunately, pre-harvest use is so common in some areas that tiny amounts of glyphosate might be measurable even in crops that weren’t sprayed.

You hate to give in to the activists and fear mongers. Nothing short of a complete ban would make them happy. And yes, pre-harvest glyphosate is a great tool and it would be sorely missed. Many farming practices would have to adjust. Swathing crops might even make a comeback.

But maybe it’s time to be proactive — better to forego one use for glyphosate than risk having all uses further stigmatized. Eliminating or at least drastically reducing glyphosate residues in food could be accomplished if pre-harvest use ended.

Kevin Hursh is an agricultural journalist, consultant and farmer. He can be reached by e-mail at

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  • richard

    Yes its hard to argue with a public who is scientifically illiterate…. Its even harder to argue with a producer who consumes nothing he produces, yet wonders why others don’t want to eat it either???

  • Welderone

    European scientists have found glyphosate to be an unsafe product. France has already put a deadline on the use of grain farmers in their country from using glyphosate. Germany is now in the process of banning glyphosate. So anyone living in Europe is scientifically literate when it comes to the use of glyphosate. As people in Canada are also when they agree with the European scientists. As far as grain farmers that are pro glyposate. I think Kevin has given you the main reason in his article. Comparatively cheap.

  • Ted Kuntz

    Clear evidence was available as early as 2009 that formulations that include glyphosate are toxic to human cells at concentrations deemed safe for human consumption. One study has shown that 93% of individuals tested show levels of glyphosate in their urine. Average levels of glyphosate in urine of children in this study eclipsed 3.5 parts per billion. This is highly disconcerting given that another
    study shows glyphosate-related damage to the liver and kidneys of rats
    at levels as low as 0.05 parts per billion.

    The recent court ruling on the carcinogenicity of glyphosate heard evidence that for four decades Monsanto maneuvered to conceal Roundup’s carcinogenicity by capturing regulatory agencies, corrupting public officials, bribing scientists and engaging in scientific fraud. There is no reason t trust Monsanto.

    But its hard to argue with those who put money ahead of health.

    • Joel Peru

      Do you a a source for the study that showed glyphosate-related damage to the liver and kidneys of rats at levels as low as 0.05 parts per billion?

      • Looks like he is talking about this study:

        “Multiomics reveal non-alcoholic fatty liver disease in rats following chronic exposure to an ultra-low dose of Roundup herbicide”

        Here is a report on why this study is flawed:

        To summarise, the study used questionable sample material from aged rats from another flawed study conducted several years earlier, and there statistical analyses was also questionable, resulting in a study with little statistical power.

      • Mike Hatt

        You might find some info from the court documents of the recent landmark court decision in the U.S.. I fall asleep reading court documents, but seriously how do you fight a system that can refute any independent study because they have financial ties? Look into the approval process for aspertame. It’s hilarious, the fda head at the time changed the rules to give his own vote a greater value because they were deadlocked at 2 votes a piece. Result was aspartame approval. Lol!

    • Mike Hatt

      I spent 15 years spraying glyphosate by way of backpack sprayer in a forestry setting. Scientifically illiterate….excuse me, but what experience does this writer have with this pesticide other than writing “opinion ” pieces, bias is quite evident here. It is quite bad, and that’s all I’ll say, because I was censored on for a lengthy post with reference material.

  • richard

    You obviously missed my point…. Clearly a large portion of the public is scientifically illiterate, a large portion of the public is illiterate period…. I was trying to compare the authors contempt of ignorance with the contempt of an intelligent consumer who witnesses a modern western producer consuming NOTHING he grows? That fact is hardly a ringing endorsement of industrial agriculture at its proponents belief in itself…….and its absurd fascination with technology….. Can you spell hypocrisy?

  • ” found evidence this causes problems with the gut at acceptable limits. A new study reveals exactly the same evidence”

    What study is this Sheryl? I asked in a previous thread and you did not answer, but if you are going to make this claim please supply the citation.

  • Mike Hatt

    The enzyme targeted by glyphosate has been found in the gut microbiome of humans. Cornucopia institute 2013.

  • I’m not seeing the link, can you post the title of the study and I will search for it myself.

    “Not saying I’m sure this is 100% the cause, but the evidence is mounting”

    That’s not evidence, that’s just an example of the post hoc ergo propter hoc fallacy. Some people you worked with are sick with undefined illnesses, so you are blaming the thing you dislike, what else were you spraying? whats your diet like? what other work were you doing? Do you exercise? Drug, alcohol or tobacco use? Far too many con-founders to draw any type of conclusion.


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