Interaction of pyroxasulfone and encapsulated saflufenacil applied preemergence to corn

Abstract A new formulation of pyroxasulfone + encapsulated saflufenacil has been developed. The encapsulated saflufenacil extends the application window to early postemergence. Pyroxasulfone, saflufenacil (suspension concentrate), and pyroxasulfone + encapsulated saflufenacil (microcapsule suspension) were applied to corn preemergence and evaluated for corn injury, corn yield, and visible weed control; in addition, the interaction (antagonistic, additive, or synergistic) was ascertained for each parameter. A total of six field trials were conducted over a two-year period (2022 and 2023) at three locations in southwestern Ontario. Pyroxasulfone was applied at 90, 120, and 150 g ai ha −1 ; saflufenacil was applied at 56, 75, and 95 g ai ha −1 ; and pyroxasulfone + encapsulated saflufenacil was applied at 146, 195, 245 g ai ha −1 , equal to the combined rates of pyroxasulfone and saflufenacil. All pyroxasulfone, encapsulated saflufenacil, and pyroxasulfone + encapsulated saflufenacil treatments caused no corn injury. Weed control varied based on application rate and weed species. Reduced weed interference with pyroxasulfone + encapsulated saflufenacil at 195 and 245 g ai ha −1 resulted in corn yield that was similar to the weed-free control and the industry standard of S -metolachlor/atrazine/mesotrione/bicyclopyrone. The interaction between pyroxasulfone and encapsulated saflufenacil for weed control was additive.