Japanese Knotweed

Summary

Latin Name

  • Fallopia japonica

What’s the problem?

  • Legal implications
  • Invasive non native species
  • Rapidity of growth and spread
  • Damage to buildings and hard surfaces
  • Does not spread by seed
  • Any part of plant capable of re-growth
  • Possible refusal of mortgage/insurance

What are the legal implications?

Possible fine or prison sentence

  • You must not allow Japanese knotweed to spread onto adjacent land - the owner of that land could take legal action against you
  • You must not allow or encourage the spread of Japanese knotweed - this includes moving contaminated soil from one place to another or incorrectly handling and transporting contaminated material and cuttings
  • You do not need to notify anyone
  • You are not obliged to remove or treat on your own land

 

In detail

Japanese knotweed does not spread from seeds. It spreads when moved and small pieces of plant or its roots are broken off - these will re-grow. One piece of root the size of a fingernail can produce a new plant. Pieces of plant or roots can be transported to a new location by:

  • Movement of contaminated soil
  • Tracked machinery picking up fragments
  • Water - particularly if plant is close to river/stream

Individual plants can cover several square metres of land and are connected by an extensive rhizome network beneath the soil surface - often quoted as being 2/3 metres deep and 7 metres in all directions from surface growth. Because of this extensive root growth beneath the ground, many chemicals will not kill the plant, even when it appears to be dying back on the surface.

Identification

  • Fleshy red tinged roots when first breaking ground
  • Large oval green heart shaped leaves
  • Silver tinge to underside of leaves
  • Hollow stem - bamboo like
  • Begins to grow in early Spring
  • Grows at a rate of 3cm per day
  • Reaches height of 1.5/2m by May
  • 3m by June
  • Leathery leaves
  • Dense clumps
  • Clusters of creamy white flowers
  • Dies back between September and November leaving dead brown stems
  • Grows in any type of soil – no matter how poor

If you have concerns over Japanese knotweed 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.