Japanese Knotweed

Japanese knotweed (Fallopia japonica) is a hardy, bamboo-like perennial plant that, although quite attractive on first glance, is highly aggressive and destructive. It was originally introduced by botanists as an ornamental garden plant in the mid nineteenth century and has now spread to such an extent that it is present in almost every 10km × 10km grid square in the country1.

Within its native range of Eastern Asia (Japan, Taiwan and China)2 it is controlled by a variety of natural pests and diseases and is rarely a problem. However, when introduced to new areas that are free from these natural population controls, Japanese knotweed can grow much larger and more vigorously, outcompeting native plants and forming barriers to important corridors for wildlife migration, along rivers, hedges and railways3. It also destroys the built environment and has been known to block footpaths, grow through concrete, damage tarmac, flood defences and homes4.

Japanese knotweed grows as much as 20 centimetres per day in any type of soil, and can reach a height of up to 3 metres in a few months4. Even though it does not produce viable seeds in the UK, its spread is almost unstoppable as it grows through rhizome fragments (underground root-like stems that can be as small as a few millimetres) meaning individual plants can cover several square metres via an extensive underground rhizome network. This makes it extremely difficult to fully remove once established. Given its virulence and the cost of eradication, it’s not hard to see why Japanese knotweed has become a major issue in property transactions. In the last few years lenders have become particularly aware and sensitive to the issue and many have formalised their secured lending decisions concerning property affected by knotweed infestations, which has resulted in mortgage refusals in some cases. It is important to be informed ‘as much as possible about whether it’s a problem in a property you’re looking at’5.

Groundsure has developed a commercial property Japanese knotweed search report suitable for conveyancers, surveyors, developers and other similar professionals. The search report highlights areas of potential Japanese knotweed infestation on the subject property and within the vicinity and environs of that site. It operates using innovative remote sensing technology and provides an estimate of the possible extent of infestation subsequent to the date of the aerial imagery used.

It is important to note that properties being offered for sale may have had cosmetic removal of Japanese knotweed, leaving a property seemingly free from infestation upon cursory inspection. The Japanese knotweed search report will provide a prior view of infestation and from there give an estimate of present day extent based upon growth rate patterns of the species. Whilst a present day view of the property from physical inspection is clearly important, the search report provides an additional degree of intelligence that is unlikely to otherwise be possible from present day physical inspection alone.

To discuss any issues relating to Japanese knotweed affecting property or to find out more about the Groundsure Japanese knotweed Search, visit www.groundsure.com or call 08444 159 000


1 GroundSure Japanese Knotweed Guide

2 http://www.nonnativespecies.org/factsheet/factsheet.cfm?speciesId=1495

3 https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/296930/LIT_2695_ df1209.pdf

4 https://www.gov.uk/japanese-knotweed-giant-hogweed-and-other-invasive-plants

5 http://www.bbc.co.uk/news/uk-30110858

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