Japanese Knotweed

**Swatty** · 14th November 2010, 02:01

We are looking to extend the site I mange. One of the hoops we went through was to get an environmental team in to check there were no lesser spotted something’s inland we were hoping to build on.
No problems with rare or protected animals/plants but we found out that there were a few areas with Japanese Knotweed on it.

• It can grow by 10cm a day
• The stem can reach three meters high and can move up to seven meters away from the plant

It’s a menace and looks like a pig to get rid of - it can damage tarmac and concrete

**markj23** · 14th November 2010, 02:30

if you dont know dont touch wait till someone tells you what to do

**ChrisBilly** · 14th November 2010, 02:39

It's illegal to move soil contaminated with japanese knotweed so probably best to contact your local council. One of the most punishable 'wildlife crimes'.

**GARY3306** · 14th November 2010, 08:24

Hmmm, horrible stuff. Reportable too, if you happen to find it you must report it. There's some fancy chemical they use and it takes a few goes I think. They used to remove the topsoil to a certain depth but I think that practice has stopped now.

**soulman** · 14th November 2010, 10:28

As been said above.needs to be reported to the enviromental ppl.This can only be tackled by specialllist

**Swatty** · 14th November 2010, 11:15

We are going down the official route with it – have been following the guidance on the government web site.

According to the advice so far you are not meant to build within 10 meters of any growth. If you are removing it you need to take away a fair bit of the earth around it – as well as going quite deep. Could end up being a significant cost (treatment and landfill)

It is a real pest of a plant – which is reflected by all the rules about how you have to deal with it. I did not know there was an issue with a plant like this – thought I would pass on the info to the members.

**rochey** · 14th November 2010, 11:25

horrid stuff i seen a grand designs or something like this with it on the land they were using and the clean up before they could build run well into thousands and thousands

**mparks8590** · 14th November 2010, 12:56

like many weed pests they can regrow from root fragments.

i've heard of people cutting the stem then injecting weekdiller directly into the stem...... obviously this takes a while to kill to the root......

and you would need to use specific weedkiller

best to get proper advice....

**neilrj** · 15th November 2010, 01:16

The proper method is to dig a huge pit, fill with the Japanese Knot Weed then pour on petrol and burn for three days, sprinkle with weedkiller, bury in concrete, and then top up the hole.

Then move!! ;-)

I think the main tactic is to bury the roots under a thin sheet of copper after it has been nuked with weedkiller but its been years since I was involved with it.

A predator insect is being tried on Knotweed in some parts of the UK so the situation should get better eventually.