Fewer than one fifth of people in Britain can identify Japanese knotweed

The findings of our annual Japanese knotweed awareness survey, undertaken on our behalf by YouGov, have been published today, following an exclusive article in the Daily Mail last weekend.

The research revealed that fewer than one fifth (19%) of Brits who say they are aware of Japanese knotweed can correctly identify the weed, despite it topping the Environment Agency’s list as “indisputably the UK’s most aggressive, destructive and invasive plant”.

When asked to pick out Japanese knotweed from a selection of five photographs, an overwhelming 81% were unable to correctly identify it, with 14% mistaking it for Bindweed, 8% selecting Houttuynia, 5% Russian Vine and 6% confusing knotweed with common Ivy, found in most British gardens.

The survey highlights a widespread lack of knowledge about Japanese knotweed, which is leaving homeowners at risk. Failure to identify and treat Japanese knotweed as soon as it appears will result in it quickly spreading and becoming established, leading to damage to buildings and rendering them unsellable until a treatment plan is implemented, with an insurance-backed guarantee to satisfy mortgage lenders.

While DIY attempts at treating Japanese knotweed can hasten its spread and make it more difficult to eradicate in the long term, at least 37% of respondents would attempt to tackle the knotweed themselves. The most popular method would be attempting to dig the knotweed out of the ground including the roots (27%), although because the plant can regrow from a piece of rhizome as small as a fingernail, this is highly unlikely to be successful. Other methods people would attempt include burning (4%), using household chemicals or diesel (4%) or covering it to deny sunlight (2%).

When it comes to selling a property affected by Japanese knotweed, three quarters (75%) of respondents would do the right thing and have the knotweed professionally treated prior to the sale. However, worryingly, 4% admit they would attempt to cover it up or otherwise conceal it, hoping it is not discovered by a potential buyer.

Only just over a third of those aware of the weed (36%), however, know that they could be sued if they allow Japanese knotweed to encroach from their property onto a neighbouring property, as proven yesterday by the failure of Network Rail’s appeal in the Waistell vs Network Rail case.

Nic Seal, Founder and MD of Environet, said: “Most people have heard of Japanese knotweed but the fact that only 19% of people in the UK can identify it from other common plants such as Bindweed and Ivy, is very concerning. 

“If left untreated Japanese knotweed will grow rapidly, by up to 10cm a day during the summer months, pushing up through cracks in concrete, cavity walls and drains. The longer it is left, the further its underground root system will spread and the more costly it will be to tackle. But it’s not just about protecting one’s property from damage and decreased value, it is also about protecting oneself from the risk of being sued if the knotweed is allowed to spread.

“The good news is that Japanese knotweed can be treated, either over two to three years using herbicide methods, or immediately by excavating it from the ground. With an insurance-backed guarantee secured for the work, most high street mortgage lenders will be happy to lend against an affected property, meaning it can still be bought and sold.”