Ryegrass resistance to glyphosate confirmed in the UK

The United Kingdom confirmed the first cases of glyphosate resistance in ryegrass in 2025 (Annual ryegrass). Occurrences were recorded in Kent, Gloucestershire, and North Yorkshire. A fourth population, in Essex, showed reduced sensitivity to the herbicide. All occurred in areas with high agronomic risk.

Three other rural properties were classified as high risk after rapid greenhouse testing. Seeds from these populations will undergo detailed analysis to confirm resistance.

The situations investigated had common features. All occurred in areas with no or low soil disturbance. The presence of larger, uncontrolled plants in the early stages was also observed. These conditions favor the selection of resistant biotypes.

According to the Weed Resistance Action Group (WRAG), the confirmed cases likely evolved independently, with no defined geographic pattern. This reinforces the importance of farm hygiene. Ryegrass seeds can be spread by agricultural machinery, such as combine harvesters and balers.