The UK Weed Resistance Action Group (WRAG) has confirmed the first instance of glyphosate resistance in a UK weed species.
Resistance to glyphosate at the maximum recommended application rate was detected in a population of Italian ryegrass (Lolium multiflorum) from a single field. This site was considered high-risk for developing glyphosate-resistant weeds, according to a press release.
In this case, large Italian ryegrass plants survived typical glyphosate rates before a late-drilled spring crop.
Since 2019, over 300 weed seed samples have been tested for herbicide resistance by ADAS and NIAB. So far, no other samples have shown glyphosate resistance, though a few additional cases are under investigation.
Globally, glyphosate resistance in Italian ryegrass has primarily been seen in North and South America, with earlier reports in Europe (Spain in 2006 and Italy in 2012). However, effective identification and management of resistant populations have prevented widespread issues.
The detection of glyphosate resistance in the UK highlights the need for farmers to follow WRAG’s resistance management guidelines as part of a proactive strategy. A reactive approach will also be necessary. This year, ADAS will screen Italian rye-grass populations that survive glyphosate applications before planting spring crops to confirm whether resistance is present or if other factors are at play.
These screenings will be conducted on live plant samples submitted by farmers or advisers. ADAS will prioritize high-risk samples and provide confidential reports to guide in-field management actions.
