Abstract
Field trials were conducted in New York during 2021 and 2022 to evaluate acifluorfen herbicide as an alternative to postemergence (POST) pigweed management for red beets (
Beta vulgaris
L. spp.
vulgaris
). Acifluorfen was applied at 0.07, 0.14, and 0.28 kg·ha
−1
a.i. to red beets at either the 6- to 8-leaf or 10- to 12-leaf developmental stages. Acifluorfen provided 68% to 96% control of Powell amaranth (
Amaranthus powellii
S. Watson), with significantly greater efficacy at higher application rates and earlier timing when weeds were smaller. Conversely, common ragweed control was considerably lower (16%–50%), likely because of the presence of larger plants at the time of application. Red beet herbicide injury, characterized by leaf necrosis, bronzing, and stunting, was significantly influenced by both the application rate and timing. Higher rates caused greater injury; applications at the 6- to 8-leaf stage resulted in substantially more damage than applications at the 10- to 12-leaf stage. Environmental conditions likely influenced injury severity, with higher rainfall and more hours of relative humidity ≥90% in 2021 causing greater leaf loss and crop stunting than in 2022. Applications of acifluorfen at the 6- to 8-leaf stage significantly reduced both red beet leaf biomass and root yield compared with the later application. These results demonstrate that acifluorfen can effectively control Powell amaranth in red beets, although application timing is crucial to minimize crop injury and yield reduction. A later application (10- to 12-leaf stage) is recommended, especially when environmental stress may exacerbate herbicide injury. Additional research is needed to fully evaluate the utility of acifluorfen in red beet production systems across diverse environments and weed pressure scenarios.