It causes havoc to gardeners and slashes property prices – and now Ipswich is said to have the third highest number of Japanese knotweed infestations in East Anglia.

Ipswich Star: Japanese knotweed can grow through hard surfaces and can return if not removed properly. Picture: ENVIRONET UKJapanese knotweed can grow through hard surfaces and can return if not removed properly. Picture: ENVIRONET UK (Image: Archant)

There were 40 infestations of the troublesome weed within 4km of the town centre, a recent study found.

This is more than the number recorded on a heatmap in February by Environet UK, an invasive species treatment service, which also ranked Ipswich as a hotspot for the plant.

Described by the Environment Agency as "indisputably the UK's most aggressive, destructive and invasive plant", Japanese knotweed grows rampantly along railways, waterways, in parks and gardens and is notoriously difficult to treat without professional help.

Lowestoft, Beccles and Stansted Airport also appeared in the top 10.

Norwich topped the list with 72 infestations within 4km of the city centre.

What is Japanese knotweed?

Japanese knotweed arrived in the UK in the 1840s.

Now in the height of growing season, it can grow at an astonishing rate of 10cm a day.

In winter, Japanese knotweed will die but by early summer bamboo-like stems emerge from deep underground.

This suppresses all other plant growth, with landscapers and gardeners finding it particularly difficult to remove by hand or get rid of it with chemicals.

Believed to have been brought to the country by the Victorians to hide railway embankments, the plant quickly became a popular addition to ornamental gardens.

The plant can also lay dormant underground for 20 years before suddenly re-growing.

How does it affect property prices?

Known globally as a menace to gardens, Japanese Knotweed can quickly spread across properties, wreaking havoc on house prices.

Nic Seal, of Environet which carried out the study of knotweed hotspots, said: "Anyone thinking about buying a property in the region, particularly in these hotspots, would be wise to check the number of infestations in the proximity of their postcode and consider instructing a Japanese knotweed survey on the property."

On top of the issues for homes, the menace also affects local rivers, destroying river banks and spreading downstream.

A spokesman for the Department for Environment, Food and Rural Affairs said: "We take the control of invasive non-native plants, such as Japanese knotweed, very seriously.

"It is illegal to plant or allow Japanese knotweed to grow in the wild and we are investing in a strategic biological control programme to manage this pest."

'Very destructive' - Ipswich gardener's experience with the weed

One Ipswich landscaper has spoken to us about how he wishes to avoid working with the plant.

"It is very destructive and a prolific grower, but I believe you can eat it, but only at certain times of the year," he said.

"Possibly the benefits of this plant could be enhanced and used in industry or to feed the hungry.

"Maybe there's some positives rather than just negatives, otherwise why would it be created by nature?"

- Tips and tricks for how to deal with Japanese knotweed can be found via the government website.