A new encapsulated saflufenacil formulation has been developed and premixed as a single product with pyroxasulfone to provide control of small-seeded annual grass and broadleaf weeds and to extend the application window to early postemergence when applied to field corn. Pyroxasulfone + encapsulated saflufenacil applied preemergence alone and in mixtures with other herbicides were examined for crop response and weed control efficacy. We hypothesized that applying pyroxasulfone + encapsulated saflufenacil with a tank-mix partner would expand the spectrum of weed species that can be controlled and improve overall weed control efficacy compared to pyroxasulfone + encapsulated saflufenacil applied alone. Six field experiments were completed at three locations in southwestern Ontario in 2022 and 2023. Pyroxasulfone + encapsulated saflufenacil was applied alone, at 146 g ai ha−1 (pyroxasulfone 90 g ai ha−1, saflufenacil 56 g ai ha−1) or 245 g ai ha−1 (pyroxasulfone 150, saflufenacil 95 g ai ha−1), and with the following herbicide partners: atrazine, dicamba, or mesotrione + atrazine. All herbicide treatments were applied prior to corn and weed emergence. Weed control, density and biomass, and corn injury and yield were assessed. All pyroxasulfone + encapsulated saflufenacil treatments caused no injury to corn. At 8 wk after emergence (WAE) pyroxasulfone + encapsulated saflufenacil (245 g ai ha−1) controlled common lambsquarters, redroot pigweed, and foxtail species by 42%, 59%, and 41%, respectively. Applications of pyroxasulfone + encapsulated saflufenacil (146 or 245 g ai ha−1) with dicamba or mesotrione + atrazine improved common lambsquarters and redroot pigweed control at 8 WAE compared with pyroxasulfone + encapsulated saflufenacil applied alone. Pyroxasulfone + encapsulated saflufenacil (146 or 245 g ai ha−1) applied with dicamba or mesotrione + atrazine provided similar control of common lambsquarters, redroot pigweed, and foxtail species to that of S-metolachlor/atrazine/mesotrione/bicyclopyrone, which is a standard herbicide used to control these weeds. Corn yield for all pyroxasulfone + encapsulated saflufenacil herbicide mixtures was similar to that of the weed-free control and the standard herbicide.

Field experiments were conducted near Beresford and South Shore, South Dakota, in 2023 and 2024, to determine weed control and soybean yield with 2,4-D and glufosinate applied individually, together, and sequentially. Herbicides were sequentially applied 12 d after an initial application. 2,4-D + glufosinate additively controlled and reduced the height of all tested weed species. Sequential applications resulted in greater control of common lambsquarters, waterhemp, redroot pigweed, and velvetleaf compared with 2,4-D or glufosinate applied alone, or 2,4-D + glufosinate applied in a mixture. The order in which herbicides were sequentially applied did not influence broadleaf weed control. Yellow foxtail control was greater with sequential applications of glufosinate. Soybean yield at Beresford was similar across all treatments. Yields were generally greater at South Shore with sequential herbicide applications when glufosinate was initially applied. The experiment results suggest that weed control and soybean yield are greater with 2,4-D + glufosinate or sequential application treatments that include 2,4-D and glufosinate.

The impact of weed density and weed distribution on irrigated corn yield was investigated in Colorado. Weed densities examined were 0,33,50, or 100% of the indigenous weed population. A series of weed distribution treatments were achieved by varying the length of the weed-free and weedy zones within the corn row while maintaining a constant weed population of 33 or 50% of the indigenous weed level. Grain yield was affected by weed density, but not by weed distribution. Each additional weed reduced corn yield 8.5 and 2.3 kg ha−1 in 1991 and 1992, respectively. When corn yields were estimated with a computer weed/corn management model, weed densities 5 to 8 wk after planting provided a better yield reduction estimate than weed densities immediately before harvest.