FMC secures first dual-mode herbicide classification for rimisoxafen

FMC Corporation said the Herbicide Resistance Action Committee has classified its new active ingredient, rimisoxafen, as a dual-mode-of-action herbicide, assigning it to HRAC Groups 12 and 32. The company described the decision as the first time the committee has granted a dual mode classification, a move that could broaden options for growers battling resistant weeds.

According to FMC, rimisoxafen simultaneously inhibits phytoene desaturase (PDS) and solanesyl diphosphate synthase (SDPS), two enzymes essential to weed development. By targeting both mechanisms, the product is designed to raise the barrier to resistance compared with single-mode herbicides. The company said trials show control of palmer amaranth and waterhemp, two broadleaf weeds that have developed resistance to multiple herbicide classes across major U.S. cropping regions.

Herbicide resistance remains a mounting challenge in global agriculture, with palmer amaranth reported to have evolved resistance to eight modes of action. FMC said rimisoxafen is intended for use in broadacre crops including corn, soybean, cereals, pulses and sunflower. Discovered at the company’s Stine Research Center, the molecule is the third new herbicide active ingredient developed by FMC in recent years, following Isoflex and Dodhylex. The company expects to begin submitting regulatory dossiers in key markets starting in 2026.