Axant™ Flex Cotton Weed Management Systems and Preemergence Palmer Amaranth Control Using Isoxaflutole
Axant™ Flex cotton is the first quadruple-stacked herbicide technology in cotton that allows the use of a herbicide novel to cotton. Isoxaflutole is an HPPD-inhibiting herbicide that will aid in the control of troublesome weeds in cotton. Axant™ Flex cotton herbicide trials were conducted near New Deal, Texas in 2021 and 2022. The objective was to evaluate Axant™ Flex cotton response and Palmer amaranth control in herbicide systems that included isoxaflutole. Crop density, visual crop response, weed control, weed density, and lint yield were assessed. Crop response never exceeded 13% in either year. Visual crop response was greater in 2021 than in 2022, possibly due to greater early-season rainfall in 2021. Preemergence treatments that included isoxaflutole provided ≥87% Palmer amaranth control 29 days after application in both years. Isoxaflutole plus fluridone was one of the best preemergence treatments in both years and provided 97 and 93% Palmer amaranth control in 2021 and 2022, respectively. When isoxaflutole at 0.11 kg ai ha-1 was used preemergence, Palmer amaranth control was ≥95% 14 days after early-postemergence applications in 2021. All treatments that included isoxaflutole preemergence controlled Palmer amaranth ≥92% 14 days after early-postemergence applications. Isoxaflutole plus fluometuron followed by (fb) glufosinate plus glyphosate plus dimethenamid-P was the only treatment that controlled Palmer amaranth ≥90% 28 days after the early-postemergence application in both years. Isoxaflutole plus fluridone fb dicamba plus glyphosate plus dimethenamid-P was the only treatment that controlled Palmer amaranth ≥90% at the end of the season. Lint yield ranged from 1,471 to 1,650 kg lint ha-1 in 2021 and 1,594 to 2,272 kg lint ha-1 in 2022, and all treatments yielded greater than the nontreated control. Axant™ Flex cotton will allow the use of isoxaflutole, which will provide a new tool for controlling troublesome weeds at-plant and in-crop.