Revealed: Suffolk's hot spots for Japanese knotweed

Fallopia japonica or Japanese knotweed. Branch with green leaves and white flowers

New research has shown that in the east of England only 18% of adults can correctly identify the invasive plant from a photograph - Credit: Getty Images/iStockphoto

Now that summer is officially here, sightings of one of the UK's most invasive species of plant are expected to soar - with several places in Suffolk identified as hot spots.

Throughout spring, Japanese knotweed emerges from the ground as purple or red asparagus-like shoots, before growing into lush green shrubs with heart or shovel-shaped leaves. It can grow up to 10cm a day between May and July and by mid-summer reach heights of around three metres. 

Japanese Knotweed expert, Environet, has created a live online tracker to help people locate and record the pest plant.

Graphic heat map showing Japanese knotweed hot spots in Suffolk in east of England

Environet's live tracking map, which helps people to record sightings of the invasive plant Japanese knotweed - Credit: Environet UK

Ipswich, Lowestoft, Stowmarket, Bury St Edmunds and Aldeburgh have all been identified as hotspots, according to Environet.

The live online tracker shows that there are 45 occurrences of Japanese knotweed within a 4km radius of of the Ipswich postcode of IP1 1AA, followed by 23 in the Lowestoft postcode of NR32 1BL and 17 in the Stowmarket's IP14 1BF.

Other areas highlighted on the heat map include the areas around Beccles and Halesworth, as well as some concentrated sightings near Saxmundham and Hollesley. 

Japanese Knotweed invading wetlands in England

Japanese knotweed can grow up to 10cm a day between May and July - Credit: Getty Images/iStockphoto


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New research suggests that only 18% of adults in the east of England can correctly identify the plant from other species commonly found in British gardens.

A recent survey of over 2,000 British adults found that over half (54%) of people in the east mistakenly identified other common garden plants such as bindweed, ivy and peony as Japanese knotweed, after looking at a series of different photographs. Bindweed, a troublesome but relatively harmless perennial, was the most commonly misidentified.

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According to Environet's research, approximately 5% of homes across the country are currently affected by the invasive plant, knocking around £20 billion off UK house prices. In the east of England, 3% of properties currently lived in are affected, and a further 2% impacted because of the plant growing on a neighbouring property.

Close up of Hedge Bindweed with white trumpet-like flowers and green heart-shaped leaves

Bindweed is one of the plants most commonly misidentified as Japanese knotweed, according to a survey - Credit: Getty Images/iStockphoto

And while it's not illegal to have Japanese knotweed on your property, you should aim to control it. Homeowners looking to sell are expected to declare it and provide a management plan.

Environet say that the general public can help in the fight against knotweed by reporting suspicious plants using the heatmap’s ‘Add Sighting’ feature and attaching a photo to be verified by experts. 

Users who want to check on an area can enter a postcode to discover the number of reported knotweed sightings nearby, and hotspots are highlighted in yellow or red, like a traffic-light system.

"Knowledge is power when it comes to Japanese knotweed and this heatmap is invaluable to homeowners and buyers who want to assess the risk in their local area," says Mat Day, Environet's regional director for East Anglia.

The fast-growing, invasive, plant Japanese Knotweed or 'or as it is also known, Polygonum cuspidatum

Despite its fearsome reputation, Japanese knotweed can be dealt with - but it's best to seek professional help. - Credit: Getty Images/iStockphoto

Mr Day says that despite its fearsome reputation, the plant can be dealt with - but it's best to seek professional help.

While it may be tempting to dig out the plant at root level, disposing of it can be challenging, as it's classed as 'controlled waste' under the Environmental Protection Act 1990, and therefore requires disposal at licensed landfill sites. It should never be included in normal household waste or put out as part of green waste collection schemes.

Back in May, Environet revealed its list of Japanese knotweed hotspots for spring across the country. Bolton in Greater Manchester came top of the list, with 621 infestations within a 4km radius, followed by Bristol with 465 and St Helens in Merseyside with 440.

What is Japanese knotweed?

Japanese knotweed was brought into the UK in the 1840s, as part of a shipment of 40 boxes of Chinese and Japanese plant species delivered to Kew Gardens. It was intended to be an ornamental garden plant, but has since become an invasive non-native species, which needs to be controlled.

According to the RHS, Japanese knotweed rarely sets seed in this country but can sprout from very small sections of creeping underground stems, known as rhizomes. It is an offence to cause it to grow in the wild.

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