Investigations of Ever Evolving Italian Ryegrass Control in Winter Wheat - Year 2

Italian ryegrass (annual ryegrass) continues to be problematic in Kentucky wheat acres and has shown rapid increases in infestations across the state. This weed species has proved to be the most problematic weed for Kentucky wheat growers with our previous research identifying multiple populations of glyphosate-resistant, pinoxaden (Axial XL), and pinoxaden plus fenoxaprop (Axial Bold) resistant annual ryegrass in Kentucky wheat fields. In the absence of a post-emergence herbicide option many Kentucky wheat growers have utilized pyroxasulfone based residual herbicides for control of ryegrass. While these preemergence herbicides have proven to be effective for suppressing fall emerging ryegrass plants, we have witnessed more ryegrass emergence in the spring months when fall applied residuals have dissipated. The previous mild Kentucky winters have likely contributed to this trend of increased spring ryegrass emergence, but also has accelerated residual herbicide degradation. Research needs to be conducted to further examine how to maximize residual herbicide for both fall and spring emerging populations of Italian ryegrass in Kentucky wheat. This research was initiated in 2023 and will be replicated across two sites in 2025 to provide four site years of data overall. Additionally, we must think beyond herbicides for future control of this weed species. The lack of potential postemergence herbicides in the very near future and limitations of currently effective preemergence herbicides call for additional control tactics such as harvest weed seed control at harvest. The University of Kentucky still has access to a Redekop seed control unit and further evaluations of potential utility of this technology is warranted. Objectives: 1. Investigate the use of residual herbicides and residual application timing for control of Italian ryegrass in wheat 2. Continue to investigate the utility of a Redekop seed control unit for reducing ryegrass seed distribution onto the field at winter wheat harvest.