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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