Illinois farmers could lose $609m a year if glyphosate is banned, study finds

On 16 July 2026 researchers at the University of Illinois Urbana-Champaign, working with the Illinois Soybean Association, released an analysis estimating that Illinois corn and soybean growers could lose between roughly $300 million and $609 million a year if the herbicide glyphosate were banned. The figure converts into about $30 to $60 an acre across more than 20 million acres of cropland, a range large enough to redraw the economics of two of the state's biggest row crops.

The estimate lands at a moment when the future of glyphosate, the active ingredient in Roundup, is being contested in courtrooms and statehouses rather than only in field-trial plots. It is one thing to model the agronomic hit; it is another to ask who pays when weed-control options narrow and input costs climb.

The number and the model

The analysis treats a hypothetical ban as a counter-factual scenario: Illinois acreage stays roughly the same, but growers lose access to the cheapest broad-spectrum herbicide on the market. In its place, farmers would be forced to mix older chemistries, run more mechanical passes and, in many cases, accept some yield drag as weeds that glyphosate once controlled reassert themselves.

Researchers anchored the loss range to two distinct assumptions about how growers would adapt. Under a low-loss scenario, growers substitute other herbicides and cultivation with relative ease, and the annual hit lands near the $300 million mark. Under a high-loss scenario, where effective substitutes are scarce, costs climb and yields slip, the modelled damage tops out at $609 million. Both numbers were drawn from yield-response and weed-pressure data that the team had already published in peer-reviewed work.

For a single Illinois farm running 1,000 acres of corn and soybeans, that works out to roughly $30,000 to $60,000 in lost margin a year, before any price effects from a national glyphosate exit are passed through. Acreage matters: most of the state's corn and soy is treated at least once with glyphosate during the growing season.

What the counter-narrative says

The economic finding sits uneasily with a separate scientific debate that has been running for years. IARC, the cancer-research arm of the World Health Organization, classified glyphosate as "probably carcinogenic to humans" in 2015. Environmental and farmworker groups have used that classification to press for state-level restrictions, retail phase-outs and litigation against the manufacturers.

Counter-evidence has piled up. The U.S. Environmental Protection Agency's most recent registration review concluded that glyphosate is "not likely to be carcinogenic to humans" when used according to label directions. Reviews by the European Food Safety Authority, Health Canada's Pest Management Regulatory Agency and Japan's Food Safety Commission have reached similar conclusions. Bayer, which inherited the Roundup portfolio through its 2018 acquisition of Monsanto, has settled tens of thousands of U.S. cancer claims while continuing to argue, in court and in regulatory filings, that the product is safe as labelled.

The Illinois model does not adjudicate that fight. It assumes the regulatory or judicial decision goes a certain way and traces the dollar consequences. Whether one accepts the IARC classification or the EPA finding, the cost number is the cost number.

The structural frame

What the Illinois study is really measuring is concentration risk. For three decades, glyphosate has been the default post-emergence herbicide in Midwestern corn and soybean rotations, paired with genetically engineered, glyphosate-tolerant seed. A ban does not just remove a chemical; it removes a system that was designed around it. Substitute chemistries exist, but they are more expensive, more numerous, and in some cases already compromised by resistant weed populations.

The study's authors flag a further wrinkle. If the United States restricted glyphosate while major competitors such as Brazil and Argentina kept using it, U.S. growers would face higher costs without any clear environmental or health gain in global herbicide use. That is the kind of asymmetry that turns a domestic regulatory debate into a trade issue.

The stakes for 2026 and beyond

For Illinois, the dollars matter because the row-crop economy is the row-crop economy. Corn and soybeans together account for the bulk of the state's harvested acres and a significant share of on-farm revenue. A $300 million to $609 million annual hit, distributed unevenly across roughly 70,000 farms, would land hardest on mid-sized operations with thin margins and little room to absorb a new input shock. Smaller farms could see a proportionally larger share of net income erased; larger operations might offset some of the loss through volume and bargaining power with input suppliers.

The political stakes are equally concrete. Illinois's two U.S. senators and its congressional delegation will, at some point in this Congress, be asked to weigh state-level restrictions, federal labeling moves and any future EPA revisit of glyphosate's registration. The new estimate gives both supporters and opponents of restrictions a number to put in the record.

What remains genuinely uncertain is the legal trajectory. The litigation against Bayer over Roundup is unresolved in several venues, and any large settlement or label change could shift the supply picture before regulators act. The Illinois study also assumes static yields and input prices; in practice, a ban would trigger substitution, breeding responses and possibly new generic entrants, all of which would soften or sharpen the dollar range. The headline number is the headline number. The real question is what happens between the model and the field.

This article tracks how Monexus framed the new Illinois glyphosate loss estimate against the wider IARC-versus-EPA dispute, surfacing the regulatory counter-evidence that tends to get cut from environmental coverage.