Giant-Rhubarbs

Common Name

  • Giant-Rhubarbs (Giant-rhubarb and Brazilian Giant-rhubarb)

Latin Name

  • Gunnera tinctoria, Gunnera manicata

What’s the problem?

  • Giant-rhubarbs are non-native species which can quickly out compete native plants in damp habitats.
  • The species are shade tolerant and often found growing besides waterbodies in dense clumps. Dense growth along waterways can impede flow and increase flood risk
  • G. tinctoria can quickly spread via seed and rhizome
  • Legal implications if allowed to spread onto neighbouring land
  • Rhizome growth can damage built structures

Legal Implications?

  • Listed as a Schedule 9 species under the Wildlife and Countryside Act 1981
  • It is an offence to plant or allow Giant-rhubarbs to spread onto adjacent land and into the wild
  • Possible fines and prison sentence under the Wildlife and Countryside Act 1981
  • It is not an offence to have Giant-rhubarbs on your land and you do not need to notify anyone on its presence on your land.
  • Soils containing Giant-rhubarbs are classified as controlled waste and should be disposed of at licensed landfill

In Detail

  • Both species are native to South America and were introduced to the UK as ornamental plants in the 19th Century.
  • The species were first recorded in the wild in 1908 (G.tinctoria) and 1935 (G. manicata) and have now become established in Western ans some lowland regions of the UK.
  • Once established the species can be invasive, forming dense colonies which can spread by seed and rhizome
  • Each flower head can produce over 250,000 seeds

Identification

  • Very large clump forming herbaceous perennial. Large umbrella like leave can grow up to 2m across, stems can grow up to 2m in height
  • Bristles and spines are present on the underside of leaf, stalks and stems  
  • Small clustered flowers form club like spikes
  • The plant is spread by rhizome and by seed
  • Leaves die down over winter, growing back in spring
  • Rhizome can grow up to 2 meters in length along the ground
  • Species can be mistaken for cultivated rhubarb and ornamental rhubarbs

Control Methods

Mechanical:

  • Flower heads can be removed to prevent the formation of seeds.
  • For smaller plants and new seedlings the rhizomes can be dug out, however if fragments of rhizome remain these can regenerate and form new plants with the potential of spreading the infestation
  • Excavated material must be disposed of at licensed landfill or buried on site

Chemical:

  • The large leaves can be effectively treated with herbicide however there are limitations in what herbicides can be used near water courses. Applications should be made late in the growing season when the leaves are fully grown
  • Multiple applications may be required for larger plants

When treating large areas, a suitable grass and forb mix should be sown to prevent bare ground and colonisation of other unwanted species.

If you have concerns over Gunnera species on your land, if you are unsure of your legal responsibilities, or, if you would like a quotation for control, please contact one of our specialist surveyors. Treatment costs start at £380.00 + VAT.