Following the first three cases of glyphosate resistance in the UK (in Kent, Gloucestershire and North Yorkshire), the Weed Resistance Action Group (WRAG) has identified more populations of Italian ryegrass in the UK that may be resistant to the herbicide glyphosate.
Following widespread publicity, ten more samples of Italian ryegrass (populations from eight farms) were identified for rapid screening, where live plant samples were potted up and sprayed with appropriate glyphosate doses by ADAS.
A high risk of resistance was identified at three farms. Population offspring will now be tested to confirm the resistance status.
All resistance cases were from high-risk crop management situations and likely evolved from independent selections (i.e. resistance was not physically spread).
In spring 2026, ADAS will screen more populations in the work funded by Bayer Crop Science.
To read the full WRAG August report, click here.
