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Dealing with invasive non-native plant species

What are Invasive Non-Native Species (INNS)?

An invasive species can be any kind of living plant organism that has been introduced outside its natural range and can cause harm. Species are given the label “invasive” when:

  • they grow and reproduce quickly
  • there are no natural mechanisms for control
  • and they spread aggressively out-competing other native species for resources

What are the best known culprits?

The most well-known and problematic plants are:

  • Japanese Knotweed: can damage concrete, tarmac and brickwork and impact on biodiversity. It spreads by underground roots - very small pieces of root can produce new plants.
  • Himalayan Balsam: impacts biodiversity by forming dense stands shading out other vegetation. It is particularly common along watercourses, along which it spread rapidly.
  • Himalayan Knotweed: which has established a presence along the River Derwent and is probably present in other, as yet unrecorded areas.

  • Giant Hogweed: can grow up to 5m tall. The stem and leaves can cause severe skin irritation and blistering. 

Who is responsible for eradicating these plants and how can I report it?

Landowners have a “responsibility” to control any invasive weeds, although it is not a legal obligation, as the natural growth and spread of these plants is not an illegal activity. It is, however, illegal to knowingly cause the spread of them ie by incorrect methods of removal or disposal. 

You can report the location of invasive species on our website.

Find out what your legal responsibility for dealing with invasive plants is and how to remove and dispose of them.

Local authorities also have some relevant powers from Section 215 of the Town and Country Planning Act 1990 which provides the authority with a discretionary power to require landowners to clean up ‘land adversely affecting the amenity of the neighbourhood’ which may be relevant to control of INNS such as Japanese knotweed.

There are many messages about how to control invasive non-native plants. The Environment Agency have written guidance notes for managing INNS.

Why are invasive species a problem?

The spread of INNS is a world-wide problem and affects parts of our borough.

They have an impact on the environment and biodiversity, crowding out native species. Some species can cause skin reactions and blistering. They can grow quickly to crowd out river basins, adding to flood risk. They cause a further risk to buildings with the potential to get into foundations and walls and to choke water courses. 

It is estimated to cost the British economy £1.7bn a year to eradicate these species.

How do I dispose of these plants?

Japanese Knotweed is classed as “controlled waste” and if cut/uprooted must be disposed of at a licensed landfill site under relevant codes of practice. Similarly, the leaves of Giant Hogweed can cause a severe skin rash. These noxious weeds and plants must not be added to general garden waste for collection. There is plenty of guidance on how to dispose of these plants properly.

What are we doing about it?

Invasive plant species are a serious environmental problem in Allerdale. Allerdale Borough Council is interested in all invasive species and treats the control of non-native species and notifiable weeds seriously. We are particularly concerned with the spread of Japanese knotweed and Himalayan balsam, which have become a problem on significant areas of council-owned land and do what we can to control them, within our limited resources either through our grounds maintenance contractor, ISS Facility Services or through the work of the Workington Nature Partnership, where volunteers have played an active role.

The latter has proved an effective way of controlling INNS on some of our more sensitive nature sites, such as our Local Nature Reserves at Siddick Pond and Harrington Reservoir, and the Grade 2 listed historic parkland at Workington Hall.

The council does not currently play an active role in controlling aquatic INNS but works with partner organisations wherever possible. The West Cumbria Rivers Trust (WCRT) focuses on aquatic and riparian invasive species and the Trust welcomes reports of INNS and the involvement of volunteers in assisting with their efforts to control them.

How you can help in the battle

We are keen to have as much information as possible about the presence of invasive plants growing on land owned by the Council. We are particularly keen to receive reports of Japanese knotweed and Himalayan balsam, which can be submitted by filling in the forms so that we can investigate.

If you see INNS along our water courses you can also help by reporting to the West Cumbria Rivers Trust.

Further reading

The Non-native Species Secretariat has responsibility for helping to coordinate the approach to invasive non-native species in Great Britain.  It reports to a Programme Board which represents the relevant governments and agencies of England, Scotland and Wales. The Non Native Species Secretariat website provide a wealth of information.

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0303 123 1702

Allerdale Borough Council
Allerdale House, Workington, Cumbria,
CA14 3YJ