Japanese knotweed

The Environment Agency states that Japanese Knotweed is the most invasive species of plant in Britain and it spreads extremely quickly, preventing native vegetation from growing.

All those who care about the Parkland Walk need to work together to eradicate the pest called Japanese Knotweed. It may also have migrated into nearby back gardens and we need to work with neighbours to stop it leapfrogging the walk boundary.

It is a problem to the construction industry as it is capable of exposing weaknesses in buildings, foundations, concrete and tarmac.

In 2013 we began a programme of injecting Knotweed with a systemic herbicide that works through the plant's root system. This work is done through the generous assistance of the City of London Corporation and Richard Payne, a Woodland Ranger based at Hampstead Heath. Since then, the occurance of Knotweed on the Walk has been reduced by 95%.

Japanese knotweed

What does it look like?

  • It is lush green in colour
  • The leaves are heart shaped
  • The stem is bamboo like in appearance
  • It produces white flowers around September or October.
  • It can grow by 10cm a day. The stem can reach three metres high and can move up to seven metres away from the plant

What to do if you find Japanese Knotweed on your premises

Landowners are not legally obliged to remove Japanese Knotweed, unless it is causing a nuisance to neighbouring property. However it is an offence to plant, or cause Japanese Knotweed to grow, in the wild.

All parts of the plant and any soil contaminated with it are classed as controlled waste, so you need to dispose of it carefully to make sure it does not spread. Be very careful if digging in the vicinity, as the tiniest of pieces of broken root will establish itself if left in the soil.

It can either be pulled out regularly to weaken it, or treated with glyphosate. Any material cut or pulled out needs to be handled with great care and must not be allowed to get into ordinary refuse or recycling collections or be left in contact with the ground. It will regrow. It needs to be bagged up carefully and disposed of by Haringey’s Parks Department who know what to do with it.

The Environment Agency has more information and downloadable management instructions at this link http://www.environment-agency.gov.uk/homeandleisure/wildlife/130079.aspx