Japanese Knotweed Part 2

Our first article on this invasive species identified what it looks like, how it grows and the structural damage it can cause to your property. This offering aims to highlight the detrimental effects it can have on your pocket.
Japanese Knotweed the real problems:
• Japanese knotweed is a difficult plant to eradicate and if left unchecked can have severe legal and financial consequences.
• Eradication is costly and can take several years.
• If you’re trying to sell a property with Knotweed problems, you will probably experience a drop in value and complications with the sale.
• If you’re applying for a mortgage it may be refused or restrictions enforced.
• Planning permission on plots with Japanese Knotweed will in most cases be refused without an acceptable eradication program in place.

Japanese Knotweed and the law
Due to its damaging ability to spread aggressively if mishandled, Japanese Knotweed is governed by several laws and acts regarding the way in which it’s treated and disposed of. Failure to use a licensed operative could leave you liable to prosecution.
In the UK there are two main pieces of legislation that cover Japanese Knotweed.
These are:
• Countryside and Wildlife Act 1981
Section 14(2) of the Wildlife & Countryside Act 1981 states
“If any person plants or otherwise causes to grow in the wild any plant which is included in part 2 of schedule 9, he shall be guilty of offence.”
Japanese Knotweed is listed in this schedule and included within this legislation. Anyone convicted under section 14 of this act is liable to a fine of £5000 and/or 6 months imprisonment, or 2 years and/or an unlimited fine on indictment.

• Environmental Protection Act 1990 (EPA)
Japanese Knotweed is classed as ‘controlled waste’ and as such must be disposed of safely at a licensed landfill site according to the Environmental Protection Act (Duty of Care) Regulations 1991. Soil containing rhizome material can be regarded as contaminated and, if taken off a site, must be disposed of at a suitably licensed landfill site and buried to a depth of at least 5 m.
An offence under the Wildlife and Countryside Act can result in a criminal prosecution. An infringement under the Environmental Protection Act can result in enforcement action being taken by the Environment Agency which can result in an unlimited fine. You can also be held liable for costs incurred from the spread of Knotweed into adjacent properties and for the disposal of infested soil off site during development which later leads to the spread of Knotweed onto another site.

If you are a vendor trying to sell property
You should employ a professional firm specialising in the eradication of Japanese knotweed as soon as possible. If you put a property on the market that is affected by Japanese knotweed the chances are that any buyer you find will pull out, incurring you in abortive fees and unnecessary stress. If you are lucky enough to find a buyer who does not need a mortgage you may well find some last minute negotiations to reduce the offered price due to the Japanese knotweed problem.
You should not try to hide the problem by cutting the knotweed down. Increasingly buyers’ solicitors are asking whether the property is or has been affected by Japanese knotweed, and if you knowingly give false information, you could be sued by your buyer for misrepresentation.

If you are a prospective buyer
You may have set your heart on a property and have now been told by your mortgage company that knotweed is present so they will not lend. However ‘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).

What to do if you have Japanese Knotweed on your property
1. Appoint a competent professional to carry out a survey to clarify if the suspect weed is in fact Japanese Knotweed and to ascertain the extent of the problem.
2. Appoint an eradication contractor to:
3. Fence off the infested area, with signage.
4. Decide on the type of eradication best suited for the particular site.
5. Implement the eradication programme.
6. Monitor the site for any future re-growth.

Control and Eradication
There are several options for dealing with Japanese Knotweed, on-site eradication with chemicals and the others deal with removal and burial of the weed material.

• Translocated herbicides such as Glyphosate and 2,4-D amine may be used in the UK in riparian areas providing consent is obtained from the Environment Agency. Treatment using the above chemicals will require several years of repeated application.
• In areas where there is no risk of run-off to watercourses and where no sensitive vegetation (including trees and shrubs) would be affected, the herbicides triclopyr, picloram and imazapyr may be used to possibly achieve control within a year. However, these are persistent in the soil and may delay planting of replacement species.
• Mechanical removal of all top growth, crowns and rhizome is another option. The advice of the Environment Agency is to remove all soil within 7m of any crowns to a depth of 3 metres. The excavated material can be buried on the site or removed off-site for treatment.

Cost Implications
The costs associated with eradicating Japanese Knotweed from a site are generally high, due to excavation costs or the costs attached to waiting for the area to be treated before developing it. Figures have been quoted at £1 per square metre for spraying and £8 for landscaping on infected sites. The costs of removal from development sites are very large; an infestation of 30m x 30m can cost developers an extra £52,785 to deal with the Knotweed.

Hope for the future
In March 2010, following a public consultation exercise, Defra approved the release of a sap sucking insect (Aphalara itadori) from Japan to biologically control Japanese knotweed in the UK. The release is initially focused on a few field trial sites, in order to gauge the effectiveness of a potential wider release. However, if this method of control is deemed to be a success, the best predicted scenario is that Japanese knotweed will be reduced to a background level in the wild, and biodiversity in areas affected by the plant will improve. However, it is highly unlikely that the law will change with regard to allowing Japanese knotweed to spread and it will probably remain a significant problem on development and residential sites.
Further information can be found at:
Cornwall Council
www.cornwall.gov.uk – There are several pages of information on the topic and the publication ‘Guidance for identification and control’ available to download.
Devon County Council
www.devon.gov.uk – Any lots of great information and the publication ‘Japanese Knotweed Downloadable Information Booklet’.
The Environment Agency
www.environment-agency.gov.uk – This site has more information on disposal and registered waste carriers, there is also a pdf to download ‘Knotweed code of practice’


Having served 16 years in the army Colin re-educated during the early 1990’s including two years at the Camborne School of Mines reading Mineral Surveying and Resource Management achieving a first class Diploma (Dip CSM). This allowed direct entry to the second year at The University of the West of England, Bristol reading Valuation and Estate Management. Training and experience was gained with Exeter City Council Estates Department and Sheperds Chartered Surveyors qualifying as a Member of the Royal Institution of Chartered Surveyors in June 2003. Colin set-up the company in May 2009 and covers the complete range of services.

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