Japanese Knotweed

[Mungler]

There’s a small bit of land that I’m looking at buying (think the size of 2 large car parking spaces) but it has knotweed on it, and which appears to have grown through under a shed from a neighbouring property on the other side of the plot. 

The land is useful to a development that I’m doing and I was planning on using it for car parking spaces ie digging it out and filling it full of concrete is probably where I would go with it anyway. 

Now, I’ve heard all sorts of horror stories about knotweed and I’d say 99% on analysis are just that, stories, up there with it growing through concrete.

So, has anyone had knotweed and successfully treated it and if so, what’s the score / cost / process and success rate.

Given that this small bit of land is next door to somewhere I own, I’m going to have to take measures anyway to make sure the weed doesn’t creep into my land and there’s a bit of me that would like to get the whole situation under control and if only to ring fence my bit and have a buffer.

The advice I have had so far is to get a syringe and inject the stems daily with concentrated glycophosphate every day for a good few weeks and so it soaks into the root system. Or rather that keeps it under control.

I’d also be intrigued as to the ball park cost from a ticketed removal expert ie how painfully expensive is that going to get.

Cheers all.

 

[dodgyrog]

Shouldn't the Council be involved? Especially if it's coming from another property.

[enfieldspares]

https://www.rhs.org.uk/weeds/japanese-knotweed

[JohnfromUK]

An architect I used was involved with another property where it was a problem.  It is notoriously difficult to 'kill' completely - and if coming in from a neighbouring property, unless they treat as well, it can keep coming back.  The problem is that the plant 'creeps' through an extensive rhizome/root system that can run very deep and be near impossible to dig out if it is near any foundations.  Whilst it doesn't 'go through concrete' - it can and does find it's way into small cracks, expansion joints etc and can spread through and come up the other side.

Injection with glyphosate does seem to work, but takes time and if not carried out on adjacent property - ingress will still happen, so it becomes a long term continuous problem.  Being a notifiable weed, it has implications for the value and legal aspects of property.  It doesn't spread by airborne or bird carried seeds apparently, but by root creep and it can go very deep and under wall foundations.

[Mice!]

Seen a few property programmes where its caused major issues. 

There are specialist companies that deal in it's treatment so it's not going to be a cheap quick fix, even digging it out the soil would have to be treated differently to normal. 

[Bigbob]

I thought the best way to treat it was inject the stems but it must be repeated for 5 years to kill it out ? Digging it out wont work as every little bit of root you break off and leave a new plant will grow from 

[discobob]

I have heard figures of 10k but that was several years ago to do a garden. I believe that they don't like copper but that could just by my middle age messing with my brain again..

[Good shot?]

4 hours ago, Bigbob said:

I thought the best way to treat it was inject the stems but it must be repeated for 5 years to kill it out ? Digging it out wont work as every little bit of root you break off and leave a new plant will grow from 

As big bob says,

that was told to me by a weed control contractor brought in by landowner of adjacent land to me that had knotweed present during building of a new housing estate.

A lot of soil was dug out and removed though.

[RockySpears]

Knotweed on property I was looking to buy.  Specialist contractor said £1,750 to treat with 10 year guarantee.  Contractor had never been called back to treated property.  It does not appear to be the horror people think it is,

 

RS

https://knotweeduk.com/

[Walker570]

30yrs ago when we moved here there was knotweed behind one of the barns which I assume had started next door.  I gave it some serious treatment with some some serious weed killer and eventually knocked it back and it did not reappear but it took me three seasons to do it.  It is like bindweed, leave 1/2 inch in the ground and it will keep growing.

[islandgun]

concrete ! or heavy black plastic..... or both

[ditchman]

get it done professionally as the contractor specialist will issue a close out report and garuntee......this will now be a passport for your piece of land and should be kept with the deeds...........

[Dave at kelton]

And if you have it within the cartilage of the property you own as a whole it could affect saleability in the future and the ability of purchasers to mortgage.

[millrace]

Cut stems carefully....and pour weedkiller direct into hollow stem before it fills with sap.....cut stems into cardboard box dry and later burn.....

[Mungler]

Thanks fellas. Some great advice here.

[garjo]

There's a case currently in the news about this:

https://metro.co.uk/2022/06/11/london-cycling-tycoon-sues-neighbours-over-japanese-knotweed-16810223/

[mel b3]

I don't know much about it other than its pretty nasty stuff . If we find it in the green waste bins at work , we have to notify defra . Even the recycling/ composting procedure doesn't kill it.