A weed resistant to the key herbicide glyphosate first found in the UK

A glyphosate-resistant weed has been detected in the UK for the first time, causing another headache for British farmers. Glyphosate is the most effective herbicide for removing vegetation before planting crops, but it is also used in other places such as home gardens, parking lots, sidewalks, vineyards and orchards. Scientists have now confirmed that the herbicide was not effective on Italian ryegrass found in many fields on a farm in Kent. Glyphosate-resistant weeds have been detected numerous times around the world in the past, but this is the first time such a case has been identified in the UK. While it is unlikely to impact food prices, glyphosate herbicide resistance has a significant financial impact on individual farmers and risks hindering the transition to more regenerative farming practices. Scientists are currently updating industry stakeholders on developments, and biosecurity measures have been tightened in the local area. It comes as farmers begin to prepare fields for spring crops in 2025 amid rising input costs, unfair supply chains, narrowing margins, increasingly severe climate impacts and anger at the government for introducing a farm inheritance tax. Weed science consultant John Cussans, who identified and confirmed Kent’s case, said it was unlikely the resistant species would spread because resistance to the herbicide glyphosate was likely due to natural selection. However, scientists still expect to detect more cases of randomly mutated Italian ryegrass on British farms in the near term as monitoring increases. Cussans said the impact could have “huge consequences” for a small number of farmers and their businesses, who will be forced to switch to more costly and harmful weed control methods and face losing access to sustainability-focused subsidies. “You could have a very small farm that’s really not very profitable, and an elderly parent who wants to pass that farm on to their children, and then glyphosate resistance will be detected,” he said. “Stepping away from academics to personal issues is a very difficult conversation and a difficult experience.” Glyphosate resistance may also have an impact on the UK’s shift towards greener practices, as regenerative farmers now use mild chemicals to clear vegetation rather than more soil-damaging techniques such as plowing and mechanical weeding. “The concern is that this could impact our ability to transform our farming system,” Cussans said. “It would be a broader threat.” Dr Helen Metcalfe, an agricultural ecologist at Rothamsted Research who studies glyphosate-free farming methods, said Kent’s case highlights the importance of moving away from over-reliance on herbicides as a method of controlling weeds. Scientists recommend that farmers use more integrated weed control methods, including using less glyphosate, mechanical weeding, diversifying crop rotations and introducing grass breaks into crop rotations to make weeds less competitive with crops. Dr Metcalfe said farmers could still use the herbicide as “one tool in the toolbox rather than as the main method of weed control”. “It is crucial that we take action now to maintain the safe management of this chemical and this is a wake-up call for us to start doing so,” she said. In recent years, scientists have stepped up resistance monitoring and testing of seed samples after Italian ryegrass was identified as a species at high risk for glyphosate resistance. Although farmers have been using glyphosate in the UK since the 1970s, the risks have increased due to increases in the species’ numbers, greater reliance on glyphosate, few alternative herbicides, and fewer farmers tilling their fields for soil health and other benefits. Scientists have previously estimated that the total loss of herbicide control of another weed, blackgrass, would cost £1 billion a year globally and £0.4 billion in England. Paul Neve, professor of crop science at the University of Copenhagen, said Italian ryegrass resistance “hasn’t become a huge problem” since the first cases in Australia in the 1990s. “The reality is that although this is a very serious economic problem, it has been around for 30 years and there is still bread on the shelves in Australia and there are still huge exports of wheat from Australia,” he said.