The UK's food security is being put at risk by herbicide-resistant black-grass, ZSL has revealed, as it calls for a ban on overuse of weed killer.

The grass out-competes wheat for soil nutrients and reduces the number of wheat plants where it grows - and it is likely to spread further across the UK.

This would increase the prices of bread and biscuits, and there would be less animal feed available so could also affect how much meat costs.

Black-grass (Alopecurus myosuroides) is a native annual weed which although natural, large infestations in farmers’ fields can force them to abandon their winter wheat – the UK’s main cereal crop.

Farmers have been using herbicides to try and tackle the black-grass problem – but ZSL has found that in many areas of England the agricultural weed is now resistant to these herbicides.

According to new research from the scientists at Rothampsted Research in Hertfordshire as well ZSL and the University of Sheffield, the cost of black-grass , is setting back the UK economy £400 million and 800,000 tonnes of lost wheat yield each year, with potential implications for national food security.

A spokesperson for ZSL said: "We must reduce herbicide use. We need government policy to address this at a national level and drive behaviour change, e.g. through a national action plan.