Evaluation of different weed management strategies including non‐chemical tools and cinmethylin for control of multiple herbicide‐resistant Alopecurus myosuroides

Abstract

The development of resistance in Alopecurus myosuroides populations to different herbicide active ingredients in Europe exacerbates efforts toward its chemical control. In Europe, cinmethylin provides an additional mode of action for the control of A. myosuroides. The objective of this study was to evaluate three resistance weed management (RWM) strategies, including cinmethylin and other pre‐emergence herbicides, for the control of multiple herbicide–resistant A. myosuroides. The RWM strategies used in this study differed in the extent of preventive cultural practices (tillage, crop rotation, sowing date and stale seedbed). Two field trials were conducted at sites with ACCase‐ and ALS‐resistant A. myosuroides biotypes in Germany between 2017 and 2020. Cinmethylin was included in the herbicide regime for A. myosuroides control. The combination of initial inversion tillage, delayed sowing, crop rotation diversification, and stale seedbed reduced the density of A. myosuroides bup to 90% compared to a strategy with pre‐emergence herbicides used as main components in control. At both sites, the amount of viable A. myosuroides seeds in the soil seed bank was reduced by over 90% after a 3‐year trial period in plots with initial inversion tillage. Molecular analyses revealed that the omission of ACCase and ALS inhibitors did not reduce the proportion of resistant A. myosuroides biotypes. Long‐term control of resistant A. myosuroides must be based on a combination of cultural practices that reduce the soil seed bank and suppress the occurrence of A. myosuroides and the use of still‐effective active ingredients for preventing the renewed entry of seeds into the soil.