When new federal rules and legal challenges put paraquat under scrutiny, alfalfa producers began looking for other spring burndown options. Albert Adjesiwor, an assistant professor and extension weed management specialist at the University of Idaho, set out to find them.

“We wanted to evaluate herbicide alternatives to paraquat so growers have reliable options if additional restrictions occur, or if paraquat disappears entirely,” Adjesiwor said.

Working with Utah State University extension agronomist Earl Creech, Adjesiwor led a two-year, multi-state study in Kimberly, Idaho, and North Logan, Utah, during 2023 and 2024. Trials compared paraquat with several potential replacements, including carfentrazone (Aim EC), saflufenacil (Sharpen), pyraflufen (Vida), tiafenacil (Reviton), diuron plus hexazinone (Velpar Alfamax), and glyphosate. These were applied to established Roundup Ready alfalfa with 2 to 4 inches of new spring growth. Researchers tracked weed control, plant height, yield, and forage quality.

Competitive control

Nearly all alternatives provided equal or better control of dandelion, flixweed, and shepherd’s purse compared with paraquat. Carfentrazone, tiafenacil, and saflufenacil temporarily stunted plants, but alfalfa recovered quickly, with no yield or quality differences by harvest. At the Utah site, saflufenacil and diuron plus hexazinone slightly reduced yield, suggesting farmers may need to delay cutting by about 10 days to allow full regrowth.

Economically, paraquat remained the lowest cost option, but pyraflufen, tiafenacil, saflufenacil, and carfentrazone were all competitive, offering a viable path forward if paraquat use becomes more restricted.

“Carfentrazone, saflufenacil, pyraflufen, tiafenacil, and diuron plus hexazinone are promising alternatives for spring weed burndown in alfalfa,” Adjesiwor concluded. “Even if paraquat goes away, growers will still have effective options.”

He noted that not all products are yet labeled for spring use, but discussions with BASF, Gowan, and Helm Agro could expand labeling and ensure producers keep multiple, safe burndown tools available.

A full copy of the final report can be found at alfalfa.org.

This article appeared in the January 2026 issue of Hay & Forage Grower on page 20 and 21.

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