Exploring the Effects of Different Stubble Tillage Practices and Glyphosate Application Combined with the New Soil Residual Herbicide Cinmethylin against <i>Alopecurus myosuroides</i> Huds. in Winter Wheat

Effective control of <i>Alopecurus myosuroides</i> Huds. (blackgrass) solely with a chemical treatment is not guaranteed anymore because populations exhibit resistance to almost all herbicide modes of action. Integrated weed management (IWM) against blackgrass is necessary to maintain high weed control efficacies in winter cereals. Four field experiments were conducted in Southwest Germany from 2018 to 2020 to control <i>A. myosuroides</i> with a combination of cultural and chemical methods. Stubble treatments, including flat, deep and inversion soil tillage; false seedbed preparation and glyphosate use, were combined with the application of the new pre-emergence herbicide cinmethylin in two rates in winter wheat. Average densities of <i>A. myosuroides</i> in the untreated control plots were up to 505 plants m⁻². The combination of different stubble management strategies and the pre-emergence herbicide cinmethylin controlled 86–97% of <i>A. myosuroides</i> plants at the low rate and 95–100% at the high rate until 120 days after sowing. The different stubble tillage practices varied in their efficacy between trials and years. Most effective and consistent were pre-sowing glyphosate application on the stubble and stale seedbed preparation with a disc harrow. Stubble treatments increased winter wheat density in the first year but had no effect on crop density in the second year. Pre-emergence application of cinmethylin did not reduce winter wheat densities. Multiple tactics of weed control, including stubble treatments and pre-emergence application of cinmethylin, provided higher and more consistent control of <i>A. myosuroides</i>. Integration of cultural weed management could prevent the herbicide resistance development.