Young prickly sow thistle seedling

In 2019, for the first time in the UK, an ALS-resistant prickly sow thistle (Sonchus asper) population was identified by ADAS researchers. 

 

This population originated from a spring wheat field in the West midlands which had an extensive history of ALS-inhibitor use. 

Glasshouse pot tests showed that this population was highly resistant to metsulfuron-methly at 4 times the recomended field rate, and was also resistant to field rates of thifensulfuron-methyl and imazamox.

Prickly sow thistle can still be controlled using other herbicides (e.g mecoprop-P) and an integrated approach (including good cultural control) can help reduce the risk of resistance. 

You can read more at: https://adas.co.uk/news/als-resistant-prickly-sowthistle-found-in-the-u…

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ADAS

ADAS provides ideas, specialist knowledge and solutions to secure our food and enhance the environment. We understand food production and the challenges and opportunities faced by organisations operating in the natural environment

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Herbicide Resistance

Herbicide resistance is the inherited ability of a weed to survive a rate of herbicide which would be lethal to a member of the normal population. It can develop over time based on repeated selection pressure imposed on the weed. This selection pressure changes the population from susceptible to resistant. Herbicide resistance is becoming an increasing problem in UK agriculture, in both grass weeds and broad-leaf weeds. See also the general topic on herbicides.

Developing strategies for reducing the risk from herbicide-resistant wild oats

Wild-oats are a highly competitive grass-weed in the UK of which there are two important species: common wild-oats (Avena fatua) and winter wild-oats (Avena sterilis ssp. ludoviciana). Failure to control wild oats in arable fields can lead to high penalties to yield, seed crop contamination, income loss for farmers and reduced competitiveness of UK agriculture. Whilst herbicide resistance selection has been slower in wild-oats compared to other grass weeds such as Black-grass (Alopecurus myosuroides), it is still a growing problem and since this report was published in 2001, resistance has been reported across hundreds of farms across many UK counties.  Continuing development of herbicide resistance in wild-oats will limit pesticide choice and possibly lead to a higher dependence on environmentally 'risky' herbicides that are more likely to reach water. The objective of this project was to conduct and collate research on the characterisation of herbicide resistance in wild-oats with the aim of informing strategies for the prevention, containment and control of herbicide resistant populations. Links to the full project are provided at the bottom of the page.

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