Fendioxypyracil, a new and systemic PPO-inhibiting herbicide for X-spectrum weed control

Abstract Background Fendioxypyracil is a novel protoporphyrinogen oxidase (PPO)–inhibiting herbicide (HRAC Group 14) developed to address the increasing prevalence of herbicide-resistant weeds and to expand available weed control options. PPO inhibitors disrupt chlorophyll biosynthesis by blocking the conversion of protoporphyrinogen IX to protoporphyrin IX, resulting in light-promoted formation of reactive oxygen species and rapid plant necrosis. Building on established PPO chemistry, fendioxypyracil incorporates a pyridine-based core and an aryloxy sidechain designed to enhance binding affinity and post-emergence activity. Results Greenhouse evaluations demonstrated high efficacy of fendioxypyracil against key grass weeds, including wild oat ( Avena fatua ), crabrass ( Digitaria Sanginalis ), goosegrass ( Eleusina indica ) and barnyard grass ( Echinochloa crus-galli ), as well as strong control of major broadleaf species. Physiological characterization and enzyme inhibition assays confirmed PPO as the primary site and mode of action, with IC₅₀ values lower than those of the commercial standard saflufenacil for both PPO isoforms. Conclusion Fendioxypyracil represents a next-generation PPO inhibitor with broad-spectrum and systemic activity, offering a valuable new tool for integrated weed management. Its high biological activity and efficacy across multiple weed taxa supports its potential to enhance on-farm weed control strategies and contributes to resistance management programs.