Most people assume that glyphosate—the active ingredient in Roundup—is only used to kill weeds before crops are even planted.
But there’s a lesser-known use that doesn’t get nearly enough attention: spraying it just before harvest to dry crops out faster.
It’s called pre-harvest desiccation, and it might be the reason glyphosate is showing up in the foods we eat—especially staples like bread, cereal, and pasta.
If you’ve ever wondered how a weed killer ends up in your breakfast, this might be the missing piece of the puzzle.
What Is Crop Desiccation—and Why Is It Done?
Desiccation is the practice of applying herbicides like glyphosate to crops shortly before harvest. The goal? To kill the plant, forcing it to dry down uniformly. This makes harvesting easier, especially when the weather is unpredictable or the crop has uneven maturity.
It’s commonly used on wheat, oats, barley, lentils, peas, chickpeas, and canola—many of which are found in everyday food products, particularly breakfast foods and baby snacks.
On the surface, it sounds practical. But here’s the problem: spraying just days before harvest doesn’t leave much time for residues to break down.
From Spraying to Serving
Unlike early-season applications where time and weather help degrade chemicals, desiccation happens right before crops are harvested. That means glyphosate can remain on the grain or seed itself—not just the plant leaves.
The result? It goes from field to food processing to your pantry. And if you’re eating bread, cereal, or crackers, chances are you’re also getting trace amounts of glyphosate—especially if the crop was imported.
This isn’t speculation. International testing has found detectable glyphosate levels in a wide range of foods, from oats to hummus. And yet in New Zealand, we’re not regularly testing for it at all.
This Isn’t a Bug—It’s a Feature
Glyphosate isn’t drifting onto crops by accident—it’s being used intentionally to kill them at just the right time. This makes desiccation an accepted agricultural practice in many parts of the world, including here in New Zealand.
So why aren’t more people talking about it?
Because it’s legal. Permitted. Even recommended in some cases. But legality doesn’t equal safety—and intent doesn’t erase consequence.
We’ve Seen This Logic Before—and It Didn’t End Well
We’ve seen this before—industries adopting short-term solutions for convenience or efficiency that carry long-term health costs. Just like nitrate runoff from over-fertilized fields, glyphosate desiccation may be one of those cases where we look back and ask, why didn’t we stop this sooner?
What the Testing (Doesn’t) Show
While countries like the U.S. have conducted limited testing on glyphosate residues in food, New Zealand has not. MPI last reported on glyphosate residues in food back in 2015–2016—and even then, only 60 samples were tested.
That’s not enough to give the public confidence. And it certainly doesn’t reflect what’s happening today.
As we explored in MPI’s Missing Glyphosate Data, we’re being asked to accept safety claims without updated evidence. That’s not reassurance. That’s regulatory faith.
A Legal Loophole—or a Quiet Rewrite?
Let’s not forget that MPI is currently proposing to raise the allowable glyphosate limits—also known as MRLs—on more than 20 food crops, including wheat, barley, oats, and peas.
Could this be a case of rewriting the rules to match what’s already happening on the ground? Raising limits because residues are already high?
It’s a question worth asking.
What Can You Do?
This isn’t just a farming practice—it’s a public health issue. And we don’t have to accept it as the status quo.
Here’s how you can take action today:
- Sign the petition to stop the proposed increase in allowable glyphosate levels on food crops. It sends a clear message: we’re watching, and we expect better.
- Support real transparency—we’re launching a series of independent tests on wheat- and oat-based breads and cereals sold right here in New Zealand. Look for the “Test Series” banners across our site, and join our mailing list to get the results first.
- Buy smart: Whenever possible, choose organic or spray-free grains, especially oats, wheat, and legumes.
- Share this article. Most people have no idea this is happening. Let’s change that—together.
Because the more we know, the less we can ignore. And the more we act, the harder we are to dismiss.
A Bitter Harvest?
We’ve been told glyphosate is safe because the levels in our food are “low.” But when the system is designed to allow that exposure—spraying crops right before harvest, raising the legal limits, and failing to test regularly—then it’s not just a matter of residues. It’s a matter of trust.
And trust, once lost, is hard to win back.
Resources & References
We’re not short on research. What’s missing is the political will to act on it—and the transparency to let the public see what’s really going on. The science is out there, hiding in plain sight. But regulation isn’t always driven by science—it’s often driven by economics.
Whitewash: The Story of a Weed Killer, Cancer, and the Corruption of Science
By Carey Gillam (2017)
An investigative exposé revealing how Monsanto manipulated scientific research and regulatory agencies to promote glyphosate, despite mounting evidence of its health risks. Gillam, a veteran journalist, provides compelling accounts of the herbicide’s impact on farmers and consumers alike.
Whitewash – [our review]
Toxic Legacy: How the Weedkiller Glyphosate Is Destroying Our Health and the Environment
By Stephanie Seneff (2021)
MIT scientist Stephanie Seneff presents a comprehensive analysis of glyphosate’s biochemical effects, linking its widespread use to various chronic diseases. The book highlights the herbicide’s impact on disrupting gut microbiota and its broader environmental implications.
Toxic Legacy – [our review]
Roundup for Breakfast? Weed Killer in Landmark Cancer Verdict Found in Kids’ Cereals, Other Oat-Based Foods
Tests found glyphosate in popular U.S. oat-based cereals.
Environmental Working Group (2018)
Human contamination by glyphosate
Laboratory tests commissioned by Friends of the Earth Europe found glyphosate residues in the urine of 44% of people tested across 18 European countries, raising concerns about widespread exposure.
Friends of the Earth Europe (2013)
Maximum Residue Levels (MRLs) for agricultural compounds in New Zealand
including the Food Notice and default MRLs.
Ministry for Primary Industries (MPI)
Pesticide Action Network UK (PAN UK) – Overview of glyphosate’s widespread use in UK agriculture, including its role as a pre-harvest desiccant and concerns over food contamination. Their Dirty Dozen report also highlights foods most likely to carry pesticide residues.
https://www.pan-uk.org/glyphosate/
https://www.pan-uk.org/dirty-dozen/
FAO/WHO Joint Meeting on Pesticide Residues (2016) – Risk assessment and residue limits.
https://www.fao.org/agriculture/crops/thematic-sitemap/theme/pests/jmpr
By the time officials admit there’s a problem, the damage is usually done. Evidence alone doesn’t create change. It takes public pressure, political courage—and people willing to ask the uncomfortable questions.
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