Diflufenican is a selective phenyl ether, Group 12 herbicide. There is limited information on the weed control efficacy of diflufenican and the potential improvement in weed control when co-applied with isoxaflutole. Three field studies were conducted in Ontario to evaluate isoxaflutole, diflufenican, and their combinations applied preemergence (PRE) for weed control in corn. Isoxaflutole at 52.5, 79, and 105 g ai ha⁻¹ provided effective control of velvetleaf (83-89%, 91-98%, and 92-97%), green pigweed (73-85%, 85-91%, and 94-97%), common ragweed (81-86%, 93-97%, and 95-97%), and common lambsquarters (88-89%, 96-99%, and 98-100%) evaluated at 2, 4, and 8 weeks after treatment (WAT), respectively. Diflufenican alone at 75-150 g ai ha⁻¹ provided ≤3% control of velvetleaf, ≤38% of green pigweed, ≤7% of common ragweed, and ≤20% of common lambsquarters. Isoxaflutole + diflufenican mixtures generally provided similar control to isoxaflutole applied alone. For barnyardgrass, isoxaflutole alone provided 16-75% control, while diflufenican was ineffective (<3%). The co-application of isoxaflutole + diflufenican improved control to 34-86%, with synergistic effects observed with barnyardgrass control at several rates and timings. Isoxaflutole and diflufenican, applied alone, controlled green foxtail at 15-72% and 0-12%, respectively. The co-application of isoxaflutole + diflufenican improved green foxtail control to 25-89% with synergistic responses at some rates and evaluation timings. There was minimal corn injury with the treatments evaluated. Weed interference reduced corn yield up to 69%. Weed interference with diflufenican alone resulted in corn yields of 4.57-4.75 T ha⁻¹ which were similar to the nontreated control (3.33 T ha⁻¹). Reduced weed interference with isoxaflutole alone and in mixtures with diflufenican resulted in corn yields of 8.36-10.83 T ha⁻¹ which were higher than both the nontreated control and diflufenican treatments. Overall, isoxaflutole provided consistent broadleaf weed control, while synergistic interactions with diflufenican enhanced barnyardgrass and green foxtail suppression.