Abstract

A newly developed formulation of pyroxasulfone and saflufenacil features encapsulated saflufenacil, enhancing corn safety and extending the application window from preemergence (PRE) to early postemergence (ePOST). Pyroxasulfone plus encapsulated saflufenacil applied ePOST alone and in herbicide mixtures were examined for weed control efficacy and corn tolerance. It was hypothesized that the application of pyroxasulfone plus encapsulated saflufenacil with an additional herbicide would improve weed control efficacy. Six field experiments were completed at three locations, in southwestern Ontario in 2022 and 2023. All herbicide treatments were applied at V1 corn (3-leaf stage). Pyroxasulfone plus encapsulated saflufenacil was applied alone, at 146 or 245 g ai ha^-1, and with the following herbicide partners: dicamba/diflufenzopyr, mesotrione + atrazine, or topramezone/dimethenamid-p + atrazine. Weed control, density, and biomass and corn injury and yield were assessed. All pyroxasulfone plus encapsulated saflufenacil herbicide mixtures caused 1 to 4, 0 to 1, and 0% corn injury at 1, 2, and 4 weeks after application (WAA), respectively. The addition of a herbicide partner to pyroxasulfone plus encapsulated saflufenacil (146 or 245 g ai ha^-1) improved common lambsquarters (Chenopodium album L.) control at 4 and 8 WAA; in contrast, there was no improvement in redroot pigweed (Amaranthus retroflexus L.) or foxtail species (Setaria spp.) control. All pyroxasulfone plus encapsulated saflufenacil herbicide mixtures provided similar control of common lambsquarters, redroot pigweed, and foxtail species with the industry standard, S-metolachlor/atrazine/mesotrione/bicyclopyrone. Corn yield for all herbicide treatments evaluated was similar to the weed-free control.

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