If you are unlucky enough to discover that you have Japanese knotweed, then a quick search of Google will soon provide you with a whole lot of specialists across the length and breadth of the UK that all claim to be able to deal with your ‘knotty’ problem. This article gives you the information you need to know yourself and also the questions you need to need to ask before you can make an informed decision as to what action to take.
This advice comes from Nic Seal from Environet UK, and he’s the first step is working out how big your problem actually is. Japanese knotweed can look quite small and contained, but looks and be deceiving and you should never take it at face value and underestimate the situation.
The plant has an extensive rhizome system extending 2 – 3 metres laterally from the visible plant and up to 3 metres deep. You get spectacular spread of the plant by disturbing the soil, as fragments of rhizome regenerate into new infestations, growing to a height of around 3m in only a couple of growing seasons. Japanese knotweed looks quite different at its various growth stages – an expert will help you look beyond the obvious.
2. Can Japanese knotweed damage my property? Yes. In its quest for water and light, Japanese knotweed can exploit any weakness in the fabric of the building – for example expansion joints in concrete, cavity walls, weaknesses in asphalt, broken mortar between paving slabs or bricks. It can also damage drains and sewers. While structural damage is rare in most residential situations, if left unchecked a mature infestation of Japanese knotweed can cause damage. If you suspect Japanese knotweed on your property, get an expert to assess the situation as soon as possible. The longer you ignore it, the more expensive the remediation.
3. Do I have a legal obligation to get rid of it? Whilst it is not illegal to have Japanese knotweed on your land, it is illegal to introduce it or to allow it to spread in the wild under the Wildlife and Countryside Act 1981. Where it encroaches on adjacent property, it frequently results in neighbour disputes. Therefore, once identified, it is best to take action.
4. Should I have a site survey? An initial discussion should help to clarify the extent of the problem and in most cases photographs will be requested prior to quoting. For larger areas and commercial development sites a good contractor will be keen to come and see the site for themselves before quoting.
5. What are my treatment options? There is more than one way to deal with the problem and the right solution for you will depend on a number of factors such as the site conditions, your plans for the site, your budget and time scales. The available methods fall into two broad categories: in situ herbicide treatment and physical removal. Make sure you have the pros and cons of all the options explained fully – they can vary greatly in terms of financial and environmental cost as well as in time taken and efficacy.
6. Is herbicide treatment the most cost effective? In situations where the soil is not going to be disturbed and you have time on your side – in other words, where there is absolutely no plan to build or develop the land in the foreseeable future – herbicide treatment is probably the most cost effective. To ensure total success though, it is usually necessary to treat the plant several times over the course of a growing season. Patience is the name of the game and using correct dosage levels is essential to the long term success of this method.
7. If I opt for excavation, can I reduce the cost by disposing of the soil myself? In short, No. Any soil contaminated with Japanese knotweed is considered ‘controlled waste’ and must be disposed of at an appropriate licensed landfill site. Under the Environmental Protection Act 1990 it is a criminal offence not to dispose of contaminated soil correctly. Using the traditional “dig and dump” method can be expensive on the wallet as well as the environment as multiple road trips in 8-wheelers to licensed disposal sites are required. It’s worth considering an on-site solution that minimises the amount of waste to landfill and allows you to reuse the soil on site. It’s a win-win for you and the environment.
8. Can I buy or sell property or land with Japanese knotweed? Whilst you can in theory buy or sell, in practice it is virtually impossible to secure finance on land or property with Japanese knotweed on or adjacent to it. In most cases this means there’s no deal until the problem is dealt with. UK banks and lending institutions are usually satisfied if an approved contractor can guarantee their treatment of the problem.
9. Is the work guaranteed? Most companies offer a guarantee but do read the small print – these guarantees are not yet insurance backed although may rely on professional indemnity insurance if things go wrong. Even more important is to make sure you have a detailed post treatment management plan agreed with your contractor. It’s easy to negate a guarantee or warranty by disturbing the soil within a year of herbicide treatment, for example.
10. Will it come back? Depending on the treatment method, and notably with herbicide treatments, there is a possibility of some minor regrowth but this should be covered in any post treatment management plan. Any regrowth is initially weak and dealt with swiftly and correctly should not pose any lasting problem.