Japanese Knotweed - Not a weed to ignore!

The impact of the discovery of Japanese Knotweed on land and buildings can prove to be very significant.  Land values can be reduced to take into account remediation works, foundations, walls and other structures can be damaged in addition to the possible refusal of a mortgage.

Source: http://www.tpknotweed.com/

Anyone who is has a garden will be more than aware of the speed in which weeds will grow, which if left uncontrolled can become unsightly and overgrown very quickly.  Having recently acquired an overgrown allotment which I have spent many hours clearing and digging I can tell you with authority that weeds are almost impossible to eradicate and therefore need to be regularly controlled.  Most varieties of weeds are harmless if regularly managed, with the exception of the odd thorny or irritant types of weeds.  There is however one particular type of weed that has received increased publicity over recent years, due to the size and rate of growth which is now deemed to be a threat to buildings and structures.  This weed has become such a risk that some mortgage lenders have refused mortgages when its presence has been identified. The culprit is Japanese Knotweed which in a recent article channel4.com/4homes (Online) (Link) states:

‘If you're buying a new home and Japanese knotweed comes up on the survey, a lender may refuse your mortgage. 'In practice, it's not usually a problem as long as a remediation plan is put in place,' says Sue Anderson, spokesperson for the Council of Mortgage Lenders (CML). 

It's clearly a worry for prospective home owners. 'We get 15 to 20 calls per week asking for advice on Japanese knotweed, often when a valuation for mortgage is made,' says Maxime Jay. 'The problem is that every mortgage lender has its own policy.'

Japanese Knotweed (Latin name - Fallopia japonica) was introduced into the UK as an ornamental plant by the Victorians. It originated from Asia in countries such as Northern China and Japan where it grew in harsh habitats on the slopes around volcanoes.  When introduced into the UK the conditions were far more fertile than those in Asia allowing the plant to thrive.  Japanese Knotweed is a Perennial Plant, meaning that it will grow for many seasons with the plant dying back in the winter and re-growing the following spring.

Japanese Knotweed is capable of growing 10cm per day.  It is highly invasive and capable of exposing weaknesses in buildings, foundations, concrete and tarmac.  It has the capability of regenerating from minute rhizomes (a root or creeping stem), therefore there is a high risk of spreading the plant from digging and other disturbance.  Effective removal of Japanese Knotweed therefore requires a specialist, which as you would expect can be expensive.

Japanese Knotweed is a serious consideration for Lenders, Developers, Purchasers, Landowners, Planners and Surveyors. The impact of the discovery of Japanese Knotweed on land and buildings can prove to be very significant.  Land values can be reduced to take into account remediation works, foundations, walls and other structures can be damaged in addition to the possible refusal of a mortgage.  It is therefore worth knowing how to identify Japanese Knotweed to firstly establish its presence and if identified how to deal with it.  Devon County Council provide an excellent guide to the identification of Japanese Knotweed on their website (Link) which is summarises below:

How to identify Japanese Knotweed

A Typical Japanese Knotweed Leaf

In the early spring red/purple shoots appear from the ground and grow rapidly forming canes.  As the canes grow the leaves gradually open 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:

During the late autumn/winter the leaves fall and the canes die and turn brown.  The canes remain standing throughout the winter and can often still be seen in new stands in the following spring and summer:

The rhizome is the underground part of the plant.  It is knotty with a leathery dark brown bark and when fresh snaps like a carrot.  Under the bark it is orange or yellow.  Inside the rhizome is a dark orange/brown central core or sometimes it is hollow with an orange, yellow or creamy outer ring, although this is variable.

Japanese Knotweed and the Law

There is a whole raft of different legislation that covers Japanese Knotweed and the summary below is taken from the Environment Agency’s Japanese Knotweed Code of Practice.  You read the Code of Practice in more detail from the following link (Link)

Japanese Knotweed is classified as controlled waste and its disposal is strictly regulated.  For example soil containing Japanese Knotweed roots/rhizomes is classified as contaminated waste and can only be taken to a licensed landfill site. Failure to dispose of Japanese Knotweed appropriately may lead to prosecution under section 34 of the Environmental Protection Act (EPA) 1990.  Also, although it is not a criminal offence to have Japanese Knotweed on your land, allowing it to grow onto neighbouring land may constitute a nuisance and as such may provide grounds for a civil action from those affected.

Other relevant legislation includes Section 14(2) of the Wildlife and Countryside Act 1981 states that “…if any person plants or otherwise causes to grow in the wild any plant which is included in Part II of Schedule 9, he shall be guilty of an offence.” Japanese knotweed is one of the plants listed in Schedule 9. Also, waste must be transferred to an authorised person, in other words a person who is either a registered carrier or exempted from registration by the Waste (England and Wales) Regulations 2011. A waste transfer note must be completed and signed giving a written description of the waste as per regulation 35 of the Waste Regulations. The Hazardous Waste Regulations 2005 contain provisions about the handling and movement of hazardous waste.

In conclusion, Japanese Knotweed seems to be receiving an increased amount of negative publicity, however given the rate at which it grows, the damage and disruption it can cause and the costs involved in dealing with it, it is easy to see why!

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