Field Notes

Why We're Still Spraying Canadian Forests With Herbicide, and Who's Actually to Blame?

Every year, helicopters and ground crews move across cutblocks in British Columbia, Ontario, New Brunswick and elsewhere in Canada, spraying glyphosate-based herbicides over regenerating forest. The goal is simple: kill the deciduous plants (aspen, birch, willow, alder) that compete with the conifer seedlings the forestry industry wants to grow into timber. It's routine. It's legal. And it's a decision we're going to regret.

What glyphosate actually does

Glyphosate is a broad-spectrum herbicide. It doesn't discriminate between a "weed" and anything else green. It works by blocking an enzyme plants need to build essential amino acids, a pathway found in plants and microorganisms but not in animals. Without that pathway, the plant's metabolism collapses and it dies over days to weeks. That's what makes it effective, and it's also why an aerial application doesn't stop neatly at the edge of a cutblock. Plants in the drift zone get hit too.

Why it's being used

The logic from industry's side is economic, not ecological. Deciduous trees like trembling aspen grow fast and shade out the young conifer seedlings that companies are obligated to establish after clear-cutting. Provincial regulations in places like B.C. push companies to prioritize conifer regeneration over deciduous growth, and hitting those milestones is tied to penalties. Manual brushing, cutting back competing vegetation by hand, is an option, but it's slower and more expensive than flying a helicopter over a block with a tank of herbicide. So spraying isn't happening because it's necessary. It's happening because it's cheap.

How much are we talking about?

In B.C., the area sprayed each year has dropped a lot since it peaked at about 40,000 hectares in 1989. But it hasn't stopped. Companies reported spraying about 340 hectares in 2024 and almost 600 hectares in 2025, mostly northeast of Prince George. Over the decades, a re-analysis of government data by The Narwhal found companies reported spraying more than 430,000 hectares across more than a million hectares of cutblocks. That's a lot of forest that was never allowed to grow back the way it wanted to.

Why governments keep allowing it

Health Canada's Pest Management Regulatory Agency finished its re-evaluation of glyphosate in 2017 and concluded it poses no unacceptable risk to human health or the environment when label directions are followed. That puts it at odds with the World Health Organization's International Agency for Research on Cancer, which classified glyphosate as a probable human carcinogen. That conflict hasn't gone away quietly. In February 2025, a Federal Court judge ruled that Health Canada's 2022 renewal of a glyphosate product was unreasonable because the agency hadn't shown it had considered newer scientific evidence, and gave it six months to make a new decision.

Politically, the gap between promises and practice is just as wide. In B.C.'s last provincial election, all three major parties campaigned on curbing or banning glyphosate in forestry. The NDP promised a phase-out. Spraying still happened in 2025, because there's no actual regulation on the books stopping it, just an unfulfilled commitment. Quebec banned herbicides in its public forests back in 2001, proof that forestry can function without it. Most other provinces simply haven't followed.

The long-term costs nobody's pricing in

Aspen, birch and the shrub layer aren't just "competition." They're fire guards, wildlife forage and pollinator habitat. Aspen stands hold moisture, resist ignition and slow fire spread far better than a stand of young conifers. Killing them off in favour of single-species conifer plantations doesn't just simplify the forest. It removes the natural buffer that would otherwise interrupt a fire's path.

Replacing a mixed, moisture-holding forest with a dense, even-aged conifer plantation creates exactly the kind of continuous, resinous fuel load that carries fire fast and hot. This isn't hypothetical. It's the pattern researchers and environmental groups have been pointing to as B.C. and other regions face increasingly severe wildfire seasons. A monoculture doesn't just burn. It burns as one continuous unit, with no deciduous breaks to slow it down.

Then there's the water. The standard industry defence is that glyphosate binds tightly to soil particles and doesn't readily leach into groundwater. That's generally true, but it assumes intact, absorbent soil. After a clear-cut, soils are often compacted, disturbed or water-repellent, especially after fire or heavy equipment traffic. When that ground meets heavy rain or a fast spring thaw, water doesn't soak in. It sheets across the surface, carrying soil particles and herbicide residue with it into the nearest stream or creek. Health Canada's own label requirements, like buffer zones around water and precautions against runoff, are basically an admission that this pathway exists. A buffer zone doesn't help much when the whole hillside is draining sideways.

And none of this is a single bad spray season. It's decades of repeated treatment across the same landscapes, compounding soil disturbance, reduced biodiversity and fire-prone plantation structure. A slow-motion trade of long-term ecological resilience for short-term timber yield.

So the honest framing here is: yes, we need wood, nobody's disputing that. The question is whether we need it produced this way, on this scale, this cheaply, or whether "we need timber" has become cover for "we want the highest-margin version of timber," and the forest and the watershed are the ones eating the difference.

And there's an irony in that worth sitting with. We pushed paper straws on people as the feel-good fix for plastic pollution, swapping the visible bad thing for the "natural" alternative, without asking what it actually takes to make paper. Pulp is trees, and turning trees into pulp is a chemically intensive, water-heavy industrial process of its own, bleaching and all. So the straw in your drink quietly moved the environmental cost from something visible, plastic in the ocean, to something a lot less visible: a watershed downstream of a pulp mill, or a cutblock that just got sprayed. Same blind spot, just moved one step back in the supply chain where nobody's looking.

And now there's the tariff squeeze

Here's a layer that doesn't get talked about enough. Canadian softwood lumber is facing about 45% in combined U.S. duties and tariffs. B.C.'s own goal is to raise the annual harvest to 45 million cubic metres, and industry groups are pushing hard to get there, while the provincial budget forecasts harvests closer to 30 million.

Think about what that pressure does. When an industry is getting squeezed that hard on margin, the incentive to cut every corner gets stronger, not weaker. Manual brushing costs more than aerial spraying. So does anything that slows the timber cycle down. The trade fight with the U.S. isn't an excuse for spraying more forest with herbicide, but it's a pretty good predictor that the corner-cutting gets worse from here, not better, unless someone actually regulates it instead of just promising to.

So who's accountable? All of them, honestly. The forestry companies choosing the cheap option. Health Canada, whose renewal of a glyphosate product a federal court found unreasonable. The provincial governments who campaigned on phasing it out and then didn't. And now, indirectly, a trade war that's giving everyone in that chain a fresh reason to keep doing what's cheapest instead of what's responsible.

The bottom line

We're managing the first five to ten years of a forest's life around timber targets, while creating conditions (flammable monocultures, compromised soil, contaminated waterways) that will play out for decades. The companies spraying know it's cheaper than manual brushing. The regulators approving it have been told by a federal court that they didn't show their work on newer science. And the people living downstream and downwind of these cutblocks are left absorbing the risk. Given what we're watching burn across this country, "cheap and fast" is starting to look like the most expensive decision we could have made.

Worth noting: PMRA scientists and regulators in several countries maintain glyphosate is safe when label directions are followed, and some foresters argue mechanical brushing has its own ecological footprint (soil disturbance, equipment emissions, worker safety) that shouldn't be waved away. The science on glyphosate and cancer remains genuinely disputed between health agencies. That's a real, unresolved disagreement, not just a talking point.

And honestly, the herbicide is only half the story. None of this spraying would be happening if we weren't clear-cutting so much forest in the first place. We chemically kill the trees that grow back on their own so the trees we planted for profit don't have to compete. That's the whole system working exactly as designed. Maybe the real long-term fix isn't a better herbicide policy. Maybe it's cutting less forest down to begin with.

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