Japanese Knotweed – Find Advice Online
Guest post by Simon Wreford, Director of Japanese Knotweed Ltd
Searching the web for advice on the best way to tackle Japanese Knotweed is confusing and the advice is contradictory.
Japanese Knotweed Ltd has a nationwide team of trained and experienced staff and some have been dealing with the knotweed problem for 15 years.
Japanese Knotweed is an invasive and resilient weed. Its roots and rhizomes can grow to a depth of 2m. Even after herbicide treatment has “eradicated” the aerial and surface growth, the deep underground rhizomes can remain in a viable state and may do so for up to twenty years. It can re-emerge and re-grow on its own accord at any time and especially if the contaminated ground is disturbed.
It is not illegal to have Japanese knotweed in your garden, but it does need to be managed.
A property is considered to be “affected” by knotweed if it is found within the boundaries of the property or close to the boundary on an adjacent property. To help understand and categorise the level of risk that the knotweed presents to the property, the Royal Institution of Chartered Surveyors (RICS) have created a “risk” table. The area around the knotweed is referred to as the “risk zone”.
When you sell your property, the buyer’s mortgage lender will want to see evidence that the property has a fully funded, long-term Knotweed Management Plan (KMP) and Guarantee in place. If the seller of a property does not disclose the presence of knotweed on the Law Society Property Information TA6 Form (3rd edition) during the purchase of the property, the seller could be guilty of a misrepresentation.
If knotweed is left to grow untreated for a number of years it has the potential to cause damage to drains, paving, paths, driveways and poorly constructed boundary walls. For this reason, it should not be ignored.
The Environment Agency state that any waste/soil taken from ground containing knotweed (dead or alive) even after a specialist has provided an herbicide treatment programme should be classified as controlled waste if removed from the site. If you are planning to landscape or build within the affected area it is prudent to excavate and remove the knotweed contaminated soil.
If knotweed encroaches onto another property the relevant law is that of private nuisance. A private nuisance is an act or omission which is an interference with, disturbance of or annoyance to a person in the exercise or enjoyment of his ownership or occupation of land. Under the Antisocial Behaviour, Crime and Policing Act 2014 councils or the police will be able to serve a notice (formerly known as an ASBO) on those failing to control Japanese knotweed.
Tackling this invasive species does need to be considered on a case-by-case basis. The prudent action is to obtain a specialist knotweed survey.
The knotweed survey includes:-
- A summary of previous control actions and site history if known.
- A thorough walkover and visual survey of as much area within the property boundary as can be inspected safely.
- A description of the knotweed stands/plants with any stands that are more than 2 metres apart identified separately.
- An assessment of all apparent site features that may affect Japanese Knotweed control action (e.g. proximity to other vegetation, services, built structures and water bodies).
- A visual inspection of the immediate property/site surroundings as far as is possible.
- A scale drawing showing the extent of the knotweed contaminated area(s) within the subject property and its location in relation to the buildings and the property boundary. The drawing will include a “risk zone” to identify the area around the knotweed that has the potential for rhizome growth.
- Neighbouring knotweed - If during the survey visit we identify knotweed in a neighbouring property that poses a threat to the subject property the location of this knotweed will be detailed on the drawing.
- The report includes the property risk category in accordance to the Royal Institute of Chartered Surveyors (RICS) (see table below). It will record any visible signs of damage believed to have been caused by the knotweed to the buildings, ancillary structures or hard standing/paving.
The treatment of knotweed can be undertaken in two ways. The weed can be repeatedly sprayed with chemical until the surface growth is “eradicated” or the entire weed and its rhizomes can be excavated. Choosing which option will be determined by the scale of the problem and the location of the knotweed in relation to the property and useable space/hard landscaping. If the affected area falls within the footprint of a proposed development/landscaping or walling the advice we give is to consider excavating and installing protective root barrier to ensure the weed cannot affect the new building/garden. If the weed is in an area of garden where a long term treatment plan can be implemented without causing a restriction in the use of the space then this is by far the cheapest management plan.
So How Do You Know its Knotweed?
Japanese Knotweed will look different throughout the seasons like most plants.
The Property Voice Insight from Richard Brown
More on the subject of Japanese Knotweed from the specialists at Japanese Knotweed Ltd, you can find their original article on treatment methods here.
What I really like about this post is the photos and descriptions of how to look for and identify the problem in different situations. The offer to review your own photos is also a simple and cost-effective way to reduce the risk and cost of a mis-doagnosis of the problem.