Grass-weed challenges, herbicide resistance status and weed control practices across crop establishment systems in Ireland’s mild Atlantic climate

The challenges of grass-weed control in a mild Atlantic climate, added to by the use non-inversion tillage and limited herbicide options necessitated on-farm knowledge acquisition on grass weeds Ireland. We surveyed 103 farms from 2020 2021 which, 62 were plough-based 41 tillage. survey comprised questionnaire determine grower demographics, challenges, adoption integrated methods (IWM); grid-square assessment key encountered one or more cereal fields both years using weed scores 0 (absent) 10 (total cover); with samples collected for herbicide-resistance testing. Across farms, Bromus spp., (62%) Avena fatua (56%) most prevalent but moderate resistance (8% acetolactate synthase (ALS)-resistant , 10% acetyl-CoA carboxylase (ACCase)-resistant A. ); Lolium multiflorum (13%) Alopecurus myosuroides (16%) found fewer higher levels (56% ACCase and/or ALS-resistant L. 43% ACCase/ALS-resistant ). Of those who adopted tillage, proportion growers practiced crop rotation (88% cereal/non-cereal break 83% alternate spring/winter-sown) used cover crops (71%) than ploughing (52-66% 19% crops), was similar systems. Despite IWM practices, had (2.2 ± 0.2 3.8 0.7) B. sterilis (1.2 2.0 0.7). Considering complex profile high resistance-risk species, there is need urgent determination effective across systems, specifically, Most aware herbicide-resistant (>80%) (>90%) practices (4 more) some extent. In our survey, tended have younger formal education larger farms. This first multi-component Ireland establishing long-term monitoring characteristics practices.