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Super-strong weeds pose greatest threat to humanity in history, scientists fear 

Super-strong weeds pose greatest threat to humanity in history, scientists fear

  • Scientists in Hertfordshire  found weeds are stronger and more abundant 
  • Resistance to herbicides, warmer temperatures and shorter crops are to blame
  • Experts said the issue poses ‘an unprecedented threat to our food security’ 

Invasive plants that pose a threat to mankind might sound like something out of the sci-fi novel Day Of The Triffids.

But it may not be so far-fetched, as scientists claim weeds now pose the greatest threat to humanity in history.

Scientists at Rothamsted Research Centre in Hertfordshire, where wheat crops have been studied since 1843, found weeds are stronger and more abundant than ever. 

Increasing resistance to herbicides, warmer temperatures and shorter crops easily shaded out by weeds are to blame. 

Experts said the issue poses ‘an unprecedented threat to our food security’. 

The study of data from 1969 found less than a third of the harvest was lost to weeds in ten years, but between 2005 and 2014 this rose to more than half.

Scientists at Rothamsted Research Centre in Hertfordshire, where wheat crops have been studied since 1843, found weeds are stronger and more abundant than ever (pictured: Japanese Knotweed) 

On plots where herbicides have never been used, yield losses to weeds have increased. 

Researchers say this is because weeds grow in a warming climate better than crops, with average temperatures at the centre around 2C higher than in 1969. 

Analysis found weeds reduced yields proportionally more with higher rates of nitrogen fertiliser. 

And herbicide use over the last 50 years has also led to weedkiller-resistant super-weeds.

Dr Jonathan Storkey, author of the study published in journal Global Change Biology, said weeds ‘represent a greater inherent threat to crop production than before the advent of herbicides’.

On plots where herbicides have never been used, yield losses to weeds have increased

On plots where herbicides have never been used, yield losses to weeds have increased

The Rothamsted Broadbalk wheat trial in Hertfordshire is the world’s longest running experiment.

Researchers have found that, on plots where herbicides have never been used, yield losses to weeds have been consistently increasing since the 1960s.

Less than a third of the harvest was lost to weeds in the first ten years of the dataset, but between 2005 and 2014, this had risen to more than half.

The team from Rothamsted Research say this is because weeds do better than crops in a warming climate, coupled with a shift towards shorter crop varieties that get shaded out by the taller weeds.

And many weed species have also benefited from increased use of nitrogen fertilisers, allowing them to grow stronger.

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