Japanese Knotweed UK map: What does Japanese Knotweed look like? Spread of KILLER plant

What is Japenese Knotweed and where did it come from?

Japanese Knotweed is a fast-growing invasive plant with bamboo-like stems and small white flowers.

Knotweed is native to Japan and considered to be an invasive species.

The plant has distinctive rhizomes or roots, which are underground structures that resemble roots, and these can be more extensive that the above-ground portion of the plant.

The invasive plant has a vigorous growth, advancing up to four inches a day in the summer.

Japanese Knotweed was introduced into the UK in the mid-nineteenth century as an ornamental plant in parks and gardens and to line railway tracks in order to stabilise the soil.

But the plant has since been dubbed one of “the most problematic species” in the country.

The notorious plant is known to strangle other plants and can kill entire gardens by depriving other plants of their key nutrients and water.

Knotweed often requires heavy-duty weedkillers or excavations to get rid of.

So far, it is estimated that it has affected more than 2 percent of development sites and 1.25 percent of residential properties across the UK, which is more than 350,000 households according to housing statistics from 2014.

What problems is it causing?

The most common problem with Japanese Knotweed is that it can cause significant damage to buildings.

In fact, some mortgage lenders have adopted stringent no-knotweed policies.

This means the value of thousands of homes have been destroyed because mortgage lenders are making it impossible for some homeowners to sell their properties.

A report by the House of Commons Science and Technology Committee published yesterday has said that banks are adopting an “overly cautious” attitude to the issue and are preventing homeowners, where there is no practical threat is imposed by the plant, from selling their homes.

The committee’s stance opposes that of UK lenders and compares the UK market to that of Europe, which apparently is far less risk-averse.

In particular, the report focuses on the continued use of the “seven-metre” proximity rule proposed by the Royal Institution of Chartered Surveyors in 2012, but which has since been discarded due to a lack of solid evidentiary support.

But research suggests that damage to the one in 80 British homes it affects is “no greater than other disruptive plants”.

The report classifies the “seven-metre rule” as a “blunt instrument” as it rarely travels more than four metres.

Where is it prevalent?

An online heatmap tracking the infestation of the invasive plant, created by Environet, shows the country as a number of severe hotspots across the UK.

The map marks the most concentrated to least concentrated areas from yellow through to red to show how prolific the plant’s presence is in certain areas.

Epicentres have been located across outer London, south and west Wales in particular between Newport and Swansea, outer Manchester and Sheffield, Nottingham

Japanese Knotweed is also prevalent around Bristol, Edinburgh and Glasgow.

Concerned residents across the UK can check whether an area is blighted by the weed using the Exposed: The Japanese Knotweed Heatmap website.

The site allows people to search by postcode to discover the number of reported sightings in that region.

It also enables people to report new sightings, which are then added to the map.