Scientists have identified a glyphosate-resistant weed on a farm in the UK for the first time, raising concerns about the controversial herbicide.
Scientists at the agricultural consultancy ADAS, said that, after reports from agronomists and screening of seed samples from a farm in Kent, they had confirmed glyphosate resistance in Italian ryegrass, an annual grass weed that particularly affects wheat fields in the UK. This is the first time glyphosate resistance in weeds has been detected in the UK.
Glyphosate is the world’s most intensively used herbicide. In the UK, it is used to prepare fields for sowing crops by clearing all vegetation from the land. It kills weeds by inhibiting EPSP synthase, an enzyme involved in plant growth, while not damaging crops that have been genetically modified to be glyphosate-tolerant.
The herbicide has been linked to increased cancer rates, and was declared a probable carcinogen by the World Health Organization in 2015.
“Globally, we lose more crop yield to weeds than we do to both insect pests and pathogens,” said Paul Neve, a professor of crop science at the University of Copenhagen. “Herbicides are the most effective tools we have, and glyphosate is one of the most effective of those.”
John Cussans, a scientist at ADAS, said that though the possibility of glyphosate resistance is a “high-risk scenario”, because of an industry-wide reliance on the herbicide, there is little risk of the resistance spreading rapidly across farms in the UK.
“But that expectation doesn’t lead to complacency,” said Cussans. “We do need to focus on biosecurity in the local area.”
The case is also a “warning sign” for farmers to reduce their reliance on glyphosate, said Helen Metcalfe, an agricultural ecologist at Rothamsted Research.
She recommended that farmers build resilience to herbicide resistance by expanding their range of weed management methods and diversifying their crop rotation. “It’s key we act now to maintain the safe stewardship of this chemical,” she said.
According to Cussans, the possibility of glyphosate resistance in British fields could have an “enormous consequence” financially on individual farmers in the UK.
“The impact is quite difficult to take for a really small business,” said Cussans. “It’s personally been quite painful to talk to individual farmers. You might have a very small farm which isn’t very profitable, and an elderly parent who wants to hand that over to their children, and glyphosate resistance is detected. It’s a tough conversation to have.”
According to ADAS, there have been 354 confirmed cases of glyphosate resistance across 57 species globally.
