THE latest research has revealed the areas across Cheshire with the highest concentration of the invasive plant species, Japanese knotweed.

Japanese knotweed usually emerges in March or April and grows rapidly to reach up to 2.5 metres in height by mid-summer. It is identifiable by its hard, bamboo-like canes and distinctive shield-shaped bright green leaves which grow in a zigzag pattern along the stem.

The plant forms dense stands, out-competing our native vegetation, it also has the potential to cause serious structural damage to our homes.

With a total of 1,305 known infestations across Cheshire, there is an average of 6 occurrences of Japanese knotweed in every 10km².

Environet - an invasive plant specialist - has now revealed that Chester is among the worst affected locations in the county for the troublesome weed.

Chester and District Standard: Japanese knotweed.Japanese knotweed.

With 110 known infestations of Japanese knotweed, the city has the fourth highest number of cases, behind Warrington (278), Widnes (121) and Northwich (113) and ahead of Macclesfield (69).

Mature plants flower in August, becoming covered in clusters of delicate tasselled creamy-white flowers. Knotweed does not produce viable seeds as all the plants in the UK are female, so it is usually spread accidentally through the movement of soil or gardening waste, or via rivers and streams when pieces of rhizome break off and take hold in new locations.

Chester and District Standard: The plant produces creamy-white flowers.The plant produces creamy-white flowers.

Tackling knotweed costs the UK economy nearly £250 million a year and homeowners are one of the groups most at risk – not only from potential damage to their property, outbuildings and gardens, which can be costly to repair, but also from legal risks arising from encroachment or when properties are sold.

Whilst it isn’t illegal to have knotweed growing on your land, if it is allowed to cross a boundary into an adjacent property, legal disputes can arise between neighbours. Similarly, when properties are sold, sellers are asked a direct question about whether knotweed is present, even if hidden beneath the ground or within 3 metres of the boundary, and those who fail to declare it can be sued by their buyer for misrepresentation.

Environet estimates that approximately 5 per cent of homes across the UK are currently affected by Japanese knotweed, either directly or neighbouring an affected property, typically impacting property prices by around 5 per cent - or up to 10 per cent in severe cases.

Nic Seal, founder of Environet, said: "Vigilance is the best way to protect your property from the risks posed by Japanese knotweed. Make sure you know what knotweed looks like and how it differs from other common garden weeds like ivy and bindweed, so you can keep an eye out for it in your garden and neighbourhood.

"Knotweed is easily identifiable during summer, but as we head through the autumn and into winter, the above-ground growth dies back and it becomes much harder to spot. It’s also easier to conceal, so anyone viewing a property to buy should be extra careful."

"There are lots of horror stories out there but the with professional help, knotweed can be successfully treated and a property’s value can be largely restored."

Further information about the distribution of Japanese knotweed can be found on Environet's Japanese Knotweed Heatmap.