The true extent of the spread of the destructive invasive species, Japanese knotweed, which can cost home owners thousands of pounds to remove, has been revealed in Suffolk.

East Anglian Daily Times: 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)

The weed, which has been known to grow through concrete, knock down walls and destroy foundations, is now prevalent across much of Britain.

However, the true extent of its infestation in Suffolk has now been revealed in a new regional study.

A heatmap has been produced by Environet UK, an invasive species treatment service, which populated the map with thousands of sightings of the plant.

It shows that there have been 37 recorded infestations within 4km of Ipswich town centre.

East Anglian Daily Times: Japanese knotweed can be identified by its thick red stem and large heart-shaped leaves. Picture: ENVIRONET UKJapanese knotweed can be identified by its thick red stem and large heart-shaped leaves. Picture: ENVIRONET UK (Image: Archant)

The presence of knotweed at a property can be a costly discovery, as removal can cost £5,000 if the plant needs to be completely removed from the ground.

The figures have prompted removal experts to reassure residents if they find knotweed at their homes, especially during the coronavirus lockdown when it may not be possible for specialists to come out and help.

Nic Seal, founder and managing director of Environet, said: “Our message to homeowners who discover Japanese knotweed growing in their garden over the next few weeks is not to panic and resist the temptation to deal with it themselves.

“In most cases knotweed can still be removed during the lockdown period, but if this isn’t possible it won’t make a huge amount of difference to leave the plant growing until restrictions are lifted.

East Anglian Daily Times: A map of the areas where infestations of Japenese knotweed are found in Suffolk: ENVIRONET UKA map of the areas where infestations of Japenese knotweed are found in Suffolk: ENVIRONET UK (Image: Archant)

“A failed attempt to dig it up could help it spread and spraying the plant with herbicide makes professional treatment more difficult further down the line.

“Where we cannot treat or remove knotweed due to current Covid-19 restrictions, we pledge to tackle at no further cost any resulting spread on clients’ property.”

Described by the Environment Agency as “indisputably the UK’s most aggressive, destructive and invasive plant”, Japanese knotweed’s rapid spread across the UK has prompted a parliamentary inquiry into its impact on the built environment.

It can be identified by its reddish-purple shoots and large heart-shaped leaves. Its flowers are creamy-white and usually appear in late summer or early autumn.

The plant generally populates more built-up areas and in Suffolk, Lowestoft and Bury St Edmunds are some of the worst affected towns.

The presence of knotweed can spell trouble for both housebuyers and sellers in these areas.

People are now required to state if Japanese knotweed is present at a property before selling and are responsible for getting a professional check.

The Royal Horticultural Society advises buyers that knotweed often results in mortgage lenders asking for assurances that it will be removed before agreeing funds. This can be expensive and delay the buying process.

However, knotweed is more prevalent in south-west England than East Anglia.