Black-grass, an herbicide-resistant weed, is causing an economic loss of more than 500 million U.S. dollars every year and also threatening food security in the UK, said a new research.

The weed is spreading at an alarming rate in the country's farmland, reducing the annual wheat yield by nearly 800,000 metric tons, estimated scientists from the Zoological Society of London (ZSL).

The annual loss, equivalent to 5 percent of the country's domestic wheat consumption, is likely to worsen in the coming years. In the worst-case scenario, the black-grass could cause an annual loss of more than 1 billion U.S. dollars, with a wheat yield loss of 3.4 million metric tons per year, the study warned.

"This study represents the first national-scale estimate of the economic costs and yield losses due to herbicide resistance, and the figure is shockingly higher than I think most would imagine," said Dr. Alexa Varah, the lead author of the study.

Overgrowth of weeds on the farms causes significant crop loss. Farmers use herbicides to control the spread of weeds on their farmland. In the last few decades, overuse and misuse of the product have led the plants to evolve and develop resistance to weed killers.

According to recent estimates, there are 253 known herbicide-resistant weeds destroying crops all over the world. In the case of black-grass, glyphosate is one of the effective products to which the weed has not developed resistance.

But evidence of farmlands with black-grass developing resistance to the product has started emerging. Furthermore, glyphosate has been linked to causing cancer, forcing a few European Union countries to take punitive actions, including banning the products in the coming years.

In order to control the situation, "we need to reduce pesticide use nationwide," Varah added. Introducing statutory limits on pesticide use, or support to farmers to encourage reduced use and adoption of alternative management strategies could help reduce the impact on the farms, researchers suggested.

The pesticide use has also significantly impacted the population of insects, farm birds and other organisms known for positively contributing to the crop yield.