Warning issued as ‘unkillable’ weed detected in UK for first time

The first documented case of Italian ryegrass resistant to one of the most effective herbicides has been detected in the UK, and it could spell trouble for farmers.

Also known as lolium multiflorum, this weed is resistant to glyphosate, one of the toughest weed killers. 

Despite a number of potential high-risk cases of Italian ryegrass found during 2018, this is the first documented case where glyphosate-resistance has been confirmed, with scientists at ADAS identifying a single field population of this weed in Kent. 

Speaking to the Daily Mail, Weed science consultant John Cussans said the discovery could be “massively consequential” for farmers.

This is because farmers will now have to mechanically dig out these weeds, which is detrimental to the soil and could mean the loss of subsidies for environmentally-friendly farming.

ADAS Principal Consultant and weed specialist John Cussans added: “We have come across several high-risk cases before where we could rule out resistance following resampling and retesting. 

“However, this is the first time we can confirm, after vigorous testing and multiple samples taken, that glyphosate resistance is present in a UK Italian ryegrass population.”

Alongside this discovery in Kent, three other suspected populations of this weed are currently under investigation.

These results are expected to be released later this year.

Italian ryegrass is the only weed with suspect populations in the UK. 

Extensive testing of black-grass and a 2023 survey of 166 brome samples found no populations with glyphosate resistance.

The Independent environmental and agricultural advice known as ADAS said: “Extensive testing of black-grass and a 2023 survey of 166 brome samples found no populations with glyphosate resistance.”

While some experts rang alarm bells following the discovery of this “unkillable” weed in England, others sounded more reassuring, mentioning countries where glyphosate-resistance hasn’t led to “widespread problems”.   

David Exwood, of the National Farmers’ Union spoke to the Daily Mail and reassured this recent discovery is nothing to be alarmed about.

He said: “Glyphosate plays a vital role in enabling farmers to produce high-quality, affordable food and deliver environmental sustainability. Resistance has been found in Spain and Italy in recent decades, but neither escalated into widespread problems.”