Report harmful or poisonous weeds

Under the Noxious Weeds Act 1959 we are responsible for controlling certain noxious weeds, including ragwort. This must be removed where it is reported as causing a nuisance to highway users or adjoining landowners.

Other invasive species being treated in Somerset are Japanese Knotweed, Himalayan Knotweed, Himalayan Balsam and Giant Hogweed.

If you know where these may be growing, please tell us and we will make sure it is dealt with in the appropriate manner.

Our environmental works seek to protect wildlife on roadside verges while maintaining road safety, consistent with the Somerset Highways Biodiversity Manual.

We use an environmentally friendly non-residual weedkiller that leaves no residue after 24 hours.

Our Weedit machine minimises the number of chemicals used by targeting weeds with a sophisticated computerised system. This has allowed us to treat more for less and is in line with our policy to reduce the number of chemicals used in highway maintenance.

Weed descriptions

Common ragwort
Highly poisonous to cattle, horses and other animals. It is not harmful to humans. This weed is a stout ragged plant which can grow to a height of 1 metre. It has long thin toothed leaves which are green on the top and have a whitish underside. It also has large clusters of yellow flowers measuring approximately 2cm across.

You can see what it looks like and find more information here

Japanese Knotweed or Himalayan Knotweed
A highly vigorous and hardy weed which can grow almost anywhere. It grows in clumps and can reach a height of 3 metres. It has a thick bamboo like stem which has a red and green pattern. Its leaves are light green, broad and triangular in shape. It can also have small white flowers.

You can see what it looks like and find more information here

Himalayan balsam
Often found on riverbanks, growing up to 2 metres in height. Each plant lasts for one year and dies at the end of the growing season. It has:

  • reddish coloured stems
  • dark green, lance-shaped leaves with jagged edges
  • flowers from June to October
  • large, brightly coloured flowers that are usually in variable shades from purple to pale pink
  • around 2,500 seeds per plant each year
  • explosive seed pods that can throw seeds over 6 metres away from the plant.

You can see what it looks like and find more information here

Giant hogweed
You should take great care when identifying giant hogweed. Contact with the plant, particularly the sap, can lead to severe blistering and scarring. Giant hogweed closely resembles native cow parsley or hogweed. It can take four years to reach its full height of 3 to 5 metres and flower (each red/white segment 50 cm). It has:

  • a reddish-purple stem with fine spines that make it appear furry like a stinging nettle
  • hollow stems
  • spotted leaf stalks
  • leaves up to 1.5 metres wide
  • flowers that show in June and July
  • flower heads that are usually 50 centimetres wide
  • flower heads capable of producing 50,000 seeds every year
  • seeds that can stay in the soil for several years before they develop

You can see what it looks like and find more information here


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Last reviewed: May 17, 2023 by Alexander

Next review due: November 17, 2023

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