Farmers warned over rise of black grass

Herbicide-resistant weeds are costing the UK economy £400m a year in lost crops, researchers say

THE UK’S food security is being put at risk by herbicide-resistant black-grass, zoologists have revealed, as they call for limits on overused weedkillers.

The grass outperforms 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, with less animal feed available, could also affect how much meat costs.

Black-grass (Alopecurus myosuroides) is a native plant, but 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 tackle the problem – but the Zoological Society of London (ZSL) has found that in many areas of England, blackgrass has developed resistance.

According to research by scientists at ZSL, Rothamsted Research in Hertfordshire and the University of Sheffield,

the cost of black-grass, is setting back the UK economy £400 million and 800,000 tons of lost wheat yield each year.

A spokesman for ZSL said: “We must reduce herbicide use. We need government policy to address this at a national level and drive behaviour change.

“Farmers must use all of the tools available to them rather than relying mainly on chemical herbicides. This will include much more diverse crop rotations, cultural control methods, direct sowing, strict field hygiene measures and regular monitoring and delayed drilling.”

The report, published in Nature

Sustainability, found the UK is losing 0.82million tons in wheat yield each year (equivalent to roughly 5 per cent of UK domestic wheat consumption) due to herbicide resistant black-grass.

In the worst-case scenario – where all fields contained large amounts of resistant black-grass – an estimated lost of 3.4million tons per year would result in an annual cost of £1billion.

Dr Alexa Varah, lead author and postdoctoral researcher at ZSL’S Institute of Zoology, said: “The figure is shockingly higher than I think most would imagine.

“We need to reduce pesticide use nationwide, which might mean introducing statutory limits on pesticide use, or support to farmers to encourage reduced use and adoption of alternative management strategies. Allocating public money for independent farm advisory services and research and development could help, too.”

Overuse of herbicides also leads to poor water quality and biodiversity loss, meaning a reduction in numbers of insects and rare farmland birds.

Glyphosate is one of the few herbicides that black-grass has not evolved a resistance to and farmers have become reliant on repeated applications to control the weed. However, evidence from a recent study shows that resistance to glyphosate is now evolving in the field, too.

Dr Varah added: “Understanding the economic and potential food security issues is a vital step, before looking at biodiversity, carbon emissions and water quality impacts in greater detail.

“We hope to use this method to help develop models to help us understand how British farmers battling blackgrass could do it in a way that is more beneficial to biodiversity like insects, mammals, wild plants and threatened farmland bird species like skylarks, lapwing and tree sparrows – unearthing how their numbers are linked to changes in farming practices.”