Japanese Knotweed Solutions

Japanese Knotweed is now one of the most problematic invasive alien species across Ireland and is a major management concern for public authorities. It is an increasingly common sight on waste ground, riverbanks and roads and is classified as one of the top 100 worst invasive species worldwide.

Japanese Knotweed has aggressively invaded natural habitats outcompeting native plants, forming tall dense stands that can grow to 2-3 metres, excluding all other vegetation. Indigenous plants cannot compete with this invasive plant and local biodiversity is reduced and endangered.


Japanese Knotweed Solutions

Japanese Knotweed can also seriously damage buildings and infrastructure, it has the ability to grow through concrete, tarmacadam and other hard standings if any cracks exist. When Japanese Knotweed takes over riverbanks, it can damage flood defence structures and undermine the ability of channels to carry flood water.

In the Republic of Ireland, at present, there are no specific legislative provisions that directly govern Japanese Knotweed control or removal. However, the Wildlife (Amendment) Act 2000 states that anyone who plants or otherwise causes to grow in a wild state in anyone who plants in the state any species of (exotic) flora, or the flowers, roots, seeds or spores of (exotic) flora shall be guilty of an offence.

The Japanese Knotweed Company offer specific packages to suit all client’s needs. Whether the infestation is large or small, residential or commercial, we offer a wide range of Japanese Knotweed solutions and eradication options.

It is our experience that there is no one size fits all when determining a Japanese Knotweed eradication strategy as no two infestations are the same, we use a number of different treatment methods or in some cases a combination of a number of methods depending on the location of the site, the age of the infestation and other site-specific pressures with regards to timescales, costs and ecological issues.

Japanese Knotweed Solutions in Ireland

Treatment Methods

Herbicide Spraying Programme:

A herbicide spraying programme can provide a cheap, effective and simple solution to treating Japanese Knotweed. It is an ideal method for doing so in parks, gardens and alongside rivers, hedgerows and railways.

The use of any herbicide treatments will be site specific and determined by initial site assessment, all relevant regulations will apply as standard.

For this to be effective the treatment needs to be applied over a number of years and away from any groundwork activities, which can make this method of treatment unsuitable for sites in the development stage.

Japanese Knotweed Solutions - Herbicide Spraying Programme

Stem Injection:

Using the stem injection technology our team applies a fast acting herbicide that kills the plant at the core. This method is used particularly in sensitive areas to eliminate the potential to damage surrounding vegetation.

Stem injection can be applied in all weathers and is particularly useful to administer near water courses, this stem injection technology can also be applied to other hollow cane species such as Giant Hogweed & Himalayan Balsam.

Japanese Knotweed Solutions - Stem Injection

Excavation followed by Stockpiling & Herbicide Treatment:

Often the next cheapest alternative compared to spraying. Excavating the Japanese Knotweed material and stockpiling elsewhere on site allows for development in the originally contaminated area to proceed without delay. An added advantage of this is that the excavation process can stimulate growth in the Knotweed that the herbicide treatment alone would not, allowing the treatment to be completed faster, making it an excellent Japanese Knotweed solution.

Japanese Knotweed Solutions - Stockpiling

Bunded Method:

The bunded method is a cost effective way of treating Japanese Knotweed. Temporary raised bunds would be located in an area of the site that will not be disturbed for a minimum of 18 months. All bunds would have a root barrier membrane to protect the underlying ground. Bunds not deeper that 400mm have shown to be the most successful. All growth of Japanese Knotweed within the bunds will be treated with herbicide in conjunction with the management plan.

Japanese Knotweed Solutions - Bunded Method

Excavation followed by sifting & burial:

The Sifting procedure aims to remove all the Japanese Knotweed material through a combination of mechanised processes. This effective and fast method of dealing with Japanese Knotweed on site means that with most sites the remediation process can be carried out within a number of weeks.

This method is the most environmentally friendly of our treatment methods as it uses no persistent herbicides, it can however be labour intensive.

Japanese Knotweed Solutions - Excavation followed by sifting & burial

Removal to landfill:

This method completely removes Japanese Knotweed material from site and is very quick to implement. Using the instant eradication method the Japanese Knotweed company technicians will fully excavate the affected land, including Rhizomes. This is then removed to an environment agency approved disposal site.

This method offers the customer a quick complete solution for construction companies and land development. It can be expensive for large areas of Japanese Knotweed due to the increasing costs of haulage. It can also raise sustainability issues.

Japanese Knotweed Solutions - Removal to landfill

Insertion of geotextile membrane:

Using a geo textile membrane the Japanese Knotweed company will create a non –permeable barrier between a building or structure to ensure the containment of the infestation thereby controlling the issue for treatment. This method can be particularly useful for people with boundary disputes of troublesome neighbours as well assisting planning applications.

Japanese Knotweed is a difficult plant to control due to its extensive underground rhizome system, therefore treatment often needs to be repeated until no regrowth is observed over several years for eradication to be achieved.

Continued monitoring of the treated areas should also be carried out to ensure that no new shoots appear.

If chemical herbicide is to be administered by a non-specialist it is very important that the dosages and timings are correct as is very easy to overdose the plant with herbicide –this results in killing off the top growth of the plant and then people get lulled into a false sense of security that their infestation has been eradicated, when in actual fact this can often force the plant’s rhizome into a dormant state (anything up to 10 years) but regrowth can occur again at any time. This regrowth is known as bonsai growth and makes further treatments less effective due to lack of exposed plant area.

It is wise to seek the best advice as soon as you become aware of the presence of any of the plant on your property, you have a responsibility to control it and prevent its spread to other properties. It must not be ignored as the longer you leave it the worse it will get and the more difficult and costly it will be to implement an effective Japanese Knotweed Solution.

As from 26th November 2015 anyone who purchases herbicides/pesticides authorised for professional use must ensure that the intended end user holds the relevant specified certificate(s). (Section 9 (5), The Plant Protection Products (Sustainable Use) Regulations 2012) & (Part III of the Food and Environment Protection Act 1985, and related Codes of Practice).


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