Petition Asks EPA to Crack Down on the Herbicide Spray That Dries Grain Before Harvest

The last spray a wheat field receives is not aimed at a weed. It is aimed at the calendar. Growers call it desiccation: applying a herbicide — most often glyphosate, the active ingredient in Roundup — in the days before harvest so the crop dries down evenly and the combine can move through on schedule. Oats, barley and wheat are the usual targets, and the practice is legal because the Environmental Protection Agency sets residue limits, known as tolerances, that allow trace amounts of the chemical to remain in the finished food.

On Thursday, the Center for Biological Diversity asked the EPA and the Department of Health and Human Services to revisit both halves of that arrangement. The petition, filed with the two agencies, asks for a joint EPA and FDA review of the risks and benefits of pre-harvest desiccation, a reassessment of the tolerances set for the herbicides used as desiccants, and new rulemaking to strengthen how the government monitors residues and sets its limits.

The specific number the group wants is 0.05 parts per million for glyphosate — a ceiling far below the current tolerance. The petition also asks the agencies to examine long-term health risks from dietary exposure to desiccant herbicides. Neither agency responded to a request for comment on the filing.

"The EPA's decision to allow our food to be sprayed with pesticides right before harvest pretty much guarantees greater exposure to dangerous chemicals in our daily meals," Nathan Donley, the center's environmental health science director, said in a statement. "It's outrageous and completely out of line with good science and basic common sense."

A fight the administration already opened

The petition lands on ground that has already shifted. In June, President Donald Trump signed an executive order on regenerative agriculture that included a directive for the EPA to make sure pre-harvest desiccant use complies with existing statutes and regulations. Health and Human Services Secretary Robert F. Kennedy Jr. criticized the practice sharply before taking office and called for a ban on using glyphosate as a desiccant, a position the Make America Healthy Again movement has pressed as well.

Residue limits are also a live file at the EPA for another reason. The agency's registration review of glyphosate is open for public comment, with the window extended through November 23 and the final review now expected to run into 2027 — a timeline we covered when the extension was announced.

The two tracks are different in kind. The registration review examines whether glyphosate can stay on the market and under what conditions. The petition filed this week goes after the narrower, more mechanical question of how much of it is allowed to remain in food, and how those numbers get chosen.

What the numbers look like now

Federal law sets tolerances at levels the EPA considers safe, and the FDA and USDA treat residues below those levels as legal and safe. Critics argue the process leans too heavily on data and input from the companies that sell the pesticides, and that the EPA frequently declines to apply the additional tenfold safety margin for infants and children that the law calls for in some cases.

The FDA's most recent sampling report gives both sides material. Pesticide residues turned up in more than 60 percent of the foods the agency analyzed. Fewer than 2 percent of domestic samples exceeded the legal limits, while roughly 15 percent of imported foods did.

Tolerances are set nationally, so any change would reach Texas grain as surely as it would reach the northern Plains. Texas elevators, flour mills and feed buyers work against the same residue standards as everyone else, and a lower glyphosate tolerance would apply to grain regardless of how it was grown. For pest control operators, the practical effect is indirect but real: the tolerance-setting process is one of the levers that determines which herbicide and insecticide products stay available and under what restrictions.

The petition is a request, not a rule. The EPA can grant it, deny it, or answer it with a Federal Register notice and a fresh comment period of its own — which is how the glyphosate review has unfolded so far.

The petition's framing is blunter than the procedural battle it triggers. "Americans deserve to have the safest and most abundant food in the world," it reads. "Protecting the quality and integrity of our daily bread and what we feed our children is one of the government's most sacred duties."