Would you know Japanese Knotweed if you saw it? You should – this invasive plant can grow through brick walls and concrete and threaten the foundations of buildings.
It wipes thousands of pounds off house values and, if found within the boundary of properties, can lead to mortgage applications being refused.
This devastating plant has been in the UK since it was introduced by a Dutch Doctor who sold it to botanical gardens in the 1840s. It grows at a rate of more than a yard a week and its wide-ranging root system can extend up to 3m deep and 7m in all directions.
The menace is not uncommon to North London gardens and eradicating it is time-consuming and costly. Treatment includes spraying or injecting herbicides into its stem, which can take up to six-months to work. Destroying just a small patch of weed costs around £1,500.
Homeowners thinking of selling are advised to tackle the weed before putting their homes on the market to avoid disappointment. Its discovery is enough to stop many banks and building societies lending and others will only lend with a certificate from a qualified company to say the problem is under control.
A recent move by the Government could see homeowners fined up to £2,500 under antisocial behaviour legislation if they allow the weed to spread from their properties.
There may be hope for a longer-term solution though, scientists hope to reduce prevalence of knotweed with insects which feed off it but it could be five to 10 years before this has an impact.
Japanese Knotweed is easy to spot. By early summer the plants are fully grown – mature canes are hollow with a distinctive purple speckle and reach up to 3 metres high. In late summer the plant flowers in spikey stems of creamy, white flowers.
For more information about Japanese Knotweed visit: https://www.rhs.org.uk/advice/profile?pid=218
