Researchers at Rothamsted Research, one of ENDURE’s UK partners, have uncovered early signs of glyphosate resistance in blackgrass, one of the country’s most harmful weeds in autumn-sown crops. The news is particularly significant as glyphosate is one of the “last lines of defence” against a weed that has already developed multiple herbicide resistance.
Blackgrass is not restricted to the UK, with problems reported across Europe, but has hit the country hard, prompting the ‘5 for 5’ initiative. This encourages farmers to take an integrated approach to blackgrass at the individual field scale for five years, employing measures from five categories (cultivation, sowing date, competition, herbicides and stopping seeding).
Writing in the journal New Phytologist, Rothamsted researchers explain how their new early warning approach combines field monitoring, glasshouse experiments and classical genetics to predict resistance risk before it occurs in the field.
The team collected blackgrass seeds from 132 farmers' fields across 11 English counties, alongside information on the how the field had been farmed over the previous seven years or so.
The Rothamstead Research website reports: “More than 16,000 seedlings were grown from these seeds in glasshouses, and the effectiveness of glyphosate in controlling plants from each local population assessed.
“Plants from nine of these populations were then cross bred to produce 400 new seed lines with known genetic pedigrees, that were also tested for their responses to glyphosate. Crucially, the team showed that the degree of sensitivity was something plants inherited from their parents, and that the variation in sensitivity between populations was a result of historical glyphosate exposure - both prerequisites for pesticide resistance evolution.
“Breeding from plants that survived glyphosate application resulted in offspring with even less herbicide sensitivity than their parents - clearly demonstrating that every generation is heading closer towards resistance than the last.”
The finding that blackgrass populations can evolve reduced sensitivity to glyphosate due to repeated exposure in farmers’ fields is particularly significant as glyphosate use has increased significantly in the UK over the past 30 years. Rothamsted Research reports that another study has estimated that a loss of control by glyphosate could reduce UK cereal and oilseed production by up to 12% at a potential cost of more than £500 million per year.
Weed ecologist David Comont told the website: “We found no evidence for high levels of resistance to glyphosate yet, though we did find that sensitivity to glyphosate was reduced in several populations. Crucially, it’s the populations from fields where glyphosate has been used more extensively which are now less sensitive to this chemical. If glyphosate use continues escalating, it may only be a matter of time before resistance evolves.”
For more information:
Last update: 24/05/2023 - ENDURE © 2009 - Contact ENDURE - Disclaimer