UK farmers face glyphosate resistance challenge for the first time

Scientists in the UK have identified the first instance of a glyphosate-resistant weed on a farm in Kent. Italian ryegrass, an annual grass weed that poses a major threat to wheat production, has shown resistance to glyphosate, the world’s most widely used herbicide. Researchers at ADAS, an agricultural consultancy, confirmed the resistance following reports from agronomists and extensive seed sample testing.

Glyphosate is a cornerstone of modern farming, widely used to clear fields of vegetation before planting crops. It acts by inhibiting an enzyme critical to plant growth, making it especially effective. However, its extensive use has also sparked global concerns, including its potential link to cancer.

Impact on Farmers

John Cussans, a weed science consultant at ADAS, noted that while the resistant ryegrass is unlikely to spread rapidly due to natural selection, the financial consequences for affected farmers could be severe. Small-scale farms with limited resources may face increased costs for alternative weed control methods. He added that the industry must prioritize glyphosate stewardship to minimize the risk of resistance spreading.

Call for Diversified Weed Management

The discovery has prompted experts to advocate for reduced reliance on glyphosate. Dr. Helen Metcalfe, an agricultural ecologist at Rothamsted Research, described the case as a “warning sign” for UK farmers. She urged farmers to adopt diversified strategies, including crop rotation and mechanical weeding, to prevent further resistance development.

Bayer’s Perspective

Bayer, a leading producer of glyphosate-based herbicides, has acknowledged the discovery as a concern but emphasized that glyphosate will remain a key component of integrated weed management. The company highlighted that this is an isolated case involving one weed species and that its own resistance monitoring program has not identified other populations of concern in the UK.

Bayer stressed the importance of proper stewardship, including using the correct herbicide dose, applying it under suitable conditions, and avoiding repeat applications to the same weeds. The company advised farmers to investigate any instances of poor control and to implement alternative chemical or non-chemical methods to manage survivors.

Appropriate steps, such as preventing the reproduction and spread of resistant weeds and maintaining good sprayer practices, are crucial to ensuring the continued efficacy of glyphosate.

Global Context and Local Measures

Globally, there have been 354 documented cases of glyphosate resistance across 57 weed species. While the Kent case remains isolated, scientists are investigating three additional suspected populations of Italian ryegrass in the UK.

The Weed Resistance Action Group (WRAG) has emphasized the importance of early intervention and adherence to established stewardship guidelines. Effective measures, such as applying correct herbicide dosages and ensuring proper application conditions, can significantly reduce the risk of resistance. As scientists continue monitoring, farmers are being encouraged to take these proactive steps.