Japanese Knotweed – Your guide to identifying and dealing with this silent invader

Japanese Knotweed is Britain’s most invasive non-native plant. It was originally brought from the Far East as an ornamental plant by the Victorians, but it has now widely naturalized and occurs across the UK as well as Europe, USA, Canada and New Zealand. Most people don’t even know it exists until it appears in their living rooms, but this silent weed is a killer for properties in Britain and an expensive one at that. In 2004, a DEFRA review of non-native species policy stated that a conservative estimate for the costs involved in eradication would be £1.56bn.

Identifying it.
In the early spring red/purple shoots appear from the ground and grow rapidly forming canes. As the canes grow the leaves gradually unfurl and turn green.
The plants are fully grown by early summer and mature canes are hollow with a distinctive purple speckle and form dense stands up to 3 metres high. The plant flowers in late summer and these consist of clusters of spiky stems covered in tiny creamy-white flowers.

How could it affect me?
Because of its regenerative properties and invasive habit Japanese Knotweed is listed under the Wildlife and Countryside Act 1981 as a plant that is not to be planted or otherwise introduced into the wild. The Environmental Protection Act 1990 also lists it as ‘controlled waste’ to be disposed of properly. You have a legal obligation not to cause it to spread if it occurs on your land.
If you have a knotweed colony on your property, it is advisable to combat it before it grows. Addressing the problem quickly is significantly quicker, cheaper and preferable to the possible consequences if it was left untouched.

In the News
Just this month a couple were reputedly forced to demolish their £300,000 four-bedroom home after it was invaded by the plant. Matthew Jones and fiancée Sue Banks saw the value of their four-bedroom house in Broxbourne, Hertfordshire, almost wiped out – reportedly dropping from £305,000 to £50,000 – as a result of the damage.
The weed pierced floorboards and skirting boards inside the property, spreading up the brick walls. Just two years before when the residents moved in, there was no sign of it, but the dangerous weed was growing on wasteland adjacent to the house and gradually crept over onto the private land.
The couple apparently fear that they may be sued for damages if the plant spreads onto neighbouring properties.

To read more about this and other ‘alien’ plant life that could affect your property, read our article on the subject here.

Japanese Knotweed is a serious issue for many homeowners and should be a concern for all prospective property purchasers. It is just one of many reasons that anybody buying a property should instruct a Chartered Surveyor to carry out a survey, identifying a problem like this could save thousands in the long term.

If you are having a property survey; a homebuyer report, house purchase survey or even a structural survey, make sure you instruct your surveyor specifically to look for Japanese Knotweed as part of the service.

Visit http://www.propertysurveying.co.ukto find a surveyor if you think plant life might be threatening your home.


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