A JAPANESE knotweed 'heatmap' has identified 42 infestations within 4km of Northwich town centre.

The 'Exposed' tracking tool has been developed by Environet UK – a company which tackles the invasive plant – to help homeowners and buyers see the potential risk to their properties.

Introduced to the UK in the 1840s as an ornamental plant, Japanese knotweed now grows rampantly along railways, waterways, in parks and gardens and is notoriously difficult to treat.

Its presence can prevent a mortgage lender approving a loan and therefore impact a property’s value by up to 10 per cent.

The Environment Agency has described it as 'indisputably the UK’s most aggressive, destructive and invasive plant', with a Parliamentary Inquiry expected to release its findings on the issue this spring.

The map also found 74 knotweed infestations in Runcorn town centre, and 41 in Chester.

Nic Seal, founder and MD of Environet, said: “This heatmap will help us build a nationwide picture of the Japanese knotweed problem and give the general public the information they need to assess the risk in their local area.

“Cheshire is a significant Japanese knotweed hotspot, particularly around the Runcorn area.

"Exposed will be a useful tool for those buying and selling property in the county and local residents who want to be aware of infestations near their homes which could spread, putting their property at risk.”

Exposed has been populated with thousands of infestations by Environet UK, which has operated across the UK for over twenty years.

It allows members of the public to enter a postcode to discover the number of reported knotweed sightings nearby. Knotweed hotspots are clearly visible in yellow or red.

The general public is encouraged to help populate the heatmap using the ‘Add Sighting’ feature and attaching a photograph of the plant so it can be verified by experts.