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Invasive species cause serious problems to utility providers, landowners, and others. These include costly delays to projects and developments. Knotweed Services (UK) Ltd has a wealth of experience in addressing, avoiding, and eliminating issues caused by invasive species.

Plant species are generally listed on Schedule 9 of the Wildlife and Countryside Act 1981 (as amended). Accordingly, it is a legal requirement to control those that appear on the list. The Infrastructure Act 2015 gives the relevant environmental authorities in England and Wales the power to issue species control orders. The orders make it possible to compel landowners or occupiers to carry out control or eradication operations.

Current list of Schedule 9 Part II Plants

Knotweed Services (UK) Ltd are a member of the Property Care Association (PCA), the UK’s foremost invasive non-native species association. Through the PCA, we work to a set of technical standards and best-practice guidance. Frequent on-site species include Japanese knotweed, Himalayan balsam, and Giant hogweed.

We provide our clients with a cost-effective solution based on the budget, the ecology and geography of the site, ensuring that we fully understand the clients aims and requirements.
Each site is unique, and our methodology for treatment is designed alongside the client to enable a swift delivery of service with minimal delays to their own work programme.
From an initial enquiry, we provide expert advice and consultation with a suitably experienced invasive species specialist.

We conduct detailed site surveys to map and identify any invasive species both on and off site.
When working on-site, we provide an experienced invasive species biosecurity supervisor who will help to ensure that work is done following relevant legislation and best practice.

Common name

Scientific name


Cabomba caroliniana

Fern, Water

Azolla filiculoides

Fig, Hottentot

Carpobrotus edulis

Hogweed, Giant

Heracleum mantegazzianum

Hyacinth, water

Eichhornia crassipes

Kelp, Giant

Macrocystis angustifolia

Kelp, Giant

Macrocystis integrifolia

Kelp, Giant

Macrocystis laevis

Kelp, Giant

Macrocystis pyrifera

Kelp, Japanese

Laminaria japonica

Knotweed, Japanese

Polygonum cuspidatum
Name changed in 2010

Leek, Few-flowered

Allium paradoxum

Lettuce, water

Pistia stratiotes


Myriophyllum aquaticum

Pennywort, Floating

Hydrocotyle ranunculoides

Salvinia, Giant

Salvinia molesta

Seafingers, Green

Codium fragile tomentosoides
Name changed in 2010

Seaweed, Californian Red

Pikea californica

Seaweed, Hooked Asparagus

Asparagopsis armata

Seaweed, Japanese

Sargassum muticum

Seaweeds, Laver

(except native species)

Porphyra spp except –
P. amethystea
P. leucosticta
P. linearis
P. miniata
P. purpurea
P. umbilicalis


Gaultheria shallon

Stonecrop, Australian swamp

Crassula helmsii


Undaria pinnatifida

Waterweed, Curly

Lagarosiphon major

The following plants were added to Schedule 9 by The Wildlife and Countryside Act 1981 (Variation of Schedule 9) (England and Wales) Order 2010:

Common name

Scientific name

Alexanders, Perfoliate

Smyrnium perfoliatum

Algae, Red

Grateloupia luxurians

Archangel, Variegated Yellow

Lamiastrum galeobdolon subsp. argentatum

Azalea, Yellow

Rhododendron luteum

Balsam, Himalayan

Impatiens glandulifera


Cotoneaster horizontalis

Cotoneaster, Entire-leaved

Cotoneaster integrifolius

Cotoneaster, Himalayan

Cotoneaster simonsii

Cotoneaster, Hollyberry

Cotoneaster bullatus

Cotoneaster, Small-leaved

Cotoneaster microphyllus

Creeper, False Virginia

Parthenocissus inserta

Creeper, Virginia

Parthenocissus quinquefolia

Dewplant, Purple

Disphyma crassifolium

Fanwort (otherwise known as Carolina Water-Shield)

Cabomba caroliniana

Fern, Water

Azolla filiculoides

Fig, Hottentot

Carpobrotus edulis

Garlic, Three-cornered

Allium triquetrum

Hyacinth, Water

Eichhornia crassipes

Knotweed, Giant

Fallopia sachalinensis

Knotweed, Hybrid

Fallopia japonica x Fallopia sachalinensis

Knotweed, Japanese

Fallopia japonica

Leek, Few-flowered

Allium paradoxum

Lettuce, Water

Pistia stratiotes


Crocosmia x crocosmiiflora

Parrot’s Feather

Myriophyllum aquaticum

Pennywort, Floating

Hydrocotyle ranunculoides

Potato, Duck

Sagittaria latifolia

Primrose, Floating Water

Ludwigia peploides

Primrose, Water

Ludwigia grandiflora

Primrose, Water

Ludwigia uruguayensis


Rhododendron ponticum


Rhododendron ponticum x Rhododendron maximum

Rhubarb, Giant

Gunnera tinctoria

Rose, Japanese

Rosa rugosa

Salvinia, Giant

Salvinia molesta

Seafingers, Green

Codium fragile

Stonecrop, Australian Swamp (otherwise known as New Zealand Pygmyweed)

Crassula helmsii

Waterweed, Curly

Lagarosiphon major


All species of the genus Elodea.


Fill in the form below, attach your pictures and we’ll let you know if the plant in your picture is Japanese Knotweed.

Determining whether any schedule 9 species are present

You may wish to consider:

  • The history of the site. Are there known infestations nearby? Has it been used for agriculture or horticulture, which can introduce invasive species? Is it likely that someone has used the site to dispose of garden or agricultural waste? Were invasive species present elsewhere in the UK and have now spread?

  • The habitat of your site. If you are working on a coastal area, there is a good chance that you will find Spartina grasses or Himalayan balsam growing near to watercourses. If you are working on wetlands, you may find Purple Loosestrife or floating pennywort. On riverbanks, look out for  Japanese knotweed. These are just some examples..

  • The time of year when you undertake your survey – this will help you determine which species might be present and whether they are likely to be flowering at that time.

  • The list of Schedule 9 plants – if any would grow in your habitat and/or climate zone then it is possible they could be found on your planned project site(s).

When might a professional ecology \ site survey report be required?

If you are planning development on a site, it is important that you consider whether invasive species may be present. If invasive plants are likely to be present and their eradication or control will affect your proposed development, then you will need to ensure that their presence and likely impact are properly considered in the planning stages of the development. 

You should get expert advice if you have any concern over whether invasive species may be present on a site; if they are not already known to be present, then their presence must be confirmed by an appropriately qualified specialist before any action is taken.

Where there is reasonable suspicion that invasive species might exist on land, a survey of the land should be carried out by someone with appropriate qualifications and experience in surveying for these invaders.

What is the best way to avoid delays to my project timeline?

To avoid delays to your project timeline, you should do the following:

  • Hire experienced invasive species specialists to get accurate results

  • Provide clear instructions on what you need from the survey and why it’s important

  • Make sure the site survey is carried out at the right time of year. For example, if it’s a winter site survey, ask if any recent works have been undertaken so it doesn’t affect results.

Hire experienced invasive species specialists like us!

Our experienced technicians are experienced in working with a range of habitats and local species to provide you with the most appropriate advice for your development.

We also have a team of invasive specialists who can help you with any invasive species that you have found on your site. If you need us to carry out an invasive species survey we will be happy to do so at the pre-planning stage, to avoid any delays later on in the project.

We can also advise on management options if you find them, or recommend potential mitigation measures to minimise their impact on your site.

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