Disruption of knotweed material can result in each knotweed fragment producing new growth. Knotweed ‘peppered’ across a site like this will be much more difficult and costly to remove.
Excavation along a site boundary reveals a heavy presence of knotweed rhizome (orange internal colour) spreading from the adjacent property under the fence. Rhizomes can grow up to 3 metres deep
Knotweed can exploit any weakness in man-made structures, such as this brick wall, pushing through the mortar when young and breaking the wall apart as it expands and matures.
The knotweed in this picture has been ineffectively removed, or perhaps even ignored, and turf laid over the top. The results are inevitable. Mowing this grass will produce cuttings contaminated with knotweed material.
Knotweed can be seen growing through and beneath a boundary fence from a mature stand in the neighbouring garden. New stems can also be seen in the background growing up through the shingle.
Knotweed grows much more prolifically close to water. Such knotweed cannot be treated with herbicide without the prior written consent of the local Environment Agency office.
Common Problems
It has been estimated that the discovery of Japanese knotweed on a development site can add around 10% to the development budget due to the cost of treatment and disposal. Left uncontrolled, it can quickly dominate a garden and spread to adjoining properties. It can also spread into foundations and boundary walls. Common problems caused by knotweed are:
- Damage to paving, tarmac, driveways, etc
- Damage to walls, foundations, etc. (knotweed has been discovered growing under suspended floors with minimal light)
- Shading of light to windows and gardens due to height of growth
- Damage to flood defence structures
- Damage to archaeological sites
- Displacing of native flora and fauna
- Reduction in land and property values
- Increased risk of flooding through dead stems washing into river and stream channels
- Increased risk of soil erosion and bank instability following removal of established stands in riparian areas
- Restriction of access to riverbanks for bank inspection and amenity use
- Accumulation of litter in mature stands
- Aesthetically displeasing
It is worth remembering that to every knotweed problem there is a solution. If you would like advice or practical assistance please contact Wreford on the number below.
Japanese knotweed blog |
What is Japanese knotweed |
Treatment methods |
On-site burial |
Root barriers |
Knotweed Management Plans |
Chemical treatment |
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