Dose-response of common lambsquarters, redroot pigweed, and foxtail species to pyroxasulfone plus encapsulated saflufenacil applied preemergence to corn

Abstract In September 2024, BASF Canada introduced a new premixture of pyroxasulfone and encapsulated saflufenacil to control weeds in corn production. Limited research has been conducted to determine the biologically effective dose of this new premixture for the control of common lambsquarters, redroot pigweed, and green foxtail. A total of six field experiments were conducted over 2 yr (2022 and 2023) at three locations in southwestern Ontario to determine the ED 50 of pyroxasulfone + encapsulated saflufenacil needed to control these three weed species. Assessment of visible weed control 8 wk after emergence determined the ED 50 for redroot pigweed, common lambsquarters, and green foxtail control to be 170, 219, and 240 g ai ha −1 , respectively. The results of this study conclude that a higher dose of pyroxasulfone + encapsulated saflufenacil is necessary for agronomically acceptable control (>80%) of these three weed species than the proposed rate (146 to 245 g ai ha −1 ) listed on the product label.