Italian ryegrass is a common weed in agricultural crops.
John Cousins
Weeds resistant to the herbicide glyphosate have been discovered for the first time in the UK. The species in question is called Italian ryegrass and is very widespread in the UK, although chemical-free specimens have only been found on one farm in Kent.
Glyphosate says it's helping farmers adopt more environmentally friendly farming practices known as regenerative agriculture John Cousins a weed management expert at consulting firm ADAS. His team confirmed that the plants were resistant in greenhouse tests.
“It could impact the ability to transition agricultural systems,” Cousins said. “Herbicide resistance to glyphosate is a real issue of great importance to farms.”
In the UK, farmers primarily use glyphosate to remove all vegetation in a field before planting. This helps avoid tillage, which compromises soil health, increases erosion and reduces carbon storage.
Minimizing soil disturbance is one of the key efforts of regenerative agriculture, along with crop rotation and ground cover maintenance.
“Glyphosate is relatively environmentally friendly compared to other pesticides,” he says. Helen Metcalf At Rothamsted Research Institute, Harpenden, UK. “It has very little bioaccumulation and low toxicity. It also supports regenerative practices such as minimal tillage, which is very good for soil health. There may be benefits.”
He says weeds are a big problem for farmers. paul nave at the University of Copenhagen, Denmark. “We lose more crop yields to weeds than to pests and pathogens.”
Around the world, Italian ryegrass (Lolium multiflorum) Glyphosate resistance is evolving and it is occurring independently in hundreds of different locations. Such weeds are a major problem for many farmers in the United States and Argentina, where crops developed to be immune to glyphosate have been grown on a large scale for years.
“But the fact is, this hasn't become a big problem, considering the first incident was 30 years ago,” Neve said.
Nave said resistant weeds are a big problem on individual farms, but they spread more slowly than insects that are resistant to pesticides, for example. Precautions such as cleaning farm equipment and removing seeds can slow the spread.
Farmers also need to employ a variety of weed control measures rather than relying solely on glyphosate, Metcalf says. “We found that if farmers focused on weed control and implemented all the alternatives to glyphosate, profits could start to recover after five to 10 years,” she says.
Cousins' team increased its surveillance in the UK in 2018, testing more than 300 samples of Italian ryegrass. He believes the resistant plants on the Kent farm were almost certainly evolved there, rather than being brought in from elsewhere.
He also said the fact that resistance appears to have taken longer to develop in the UK than in other countries means that British farmers have not genetically modified or conventionally bred crops to be resistant to glyphosate. They also think that this may be because they are not growing crops that are not cultivated. In such crops, glyphosate can be applied to control weeds before planting as well as during crop growth.
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Source: www.newscientist.com
