Japanese Knotweed

Can someone please advise how I can get rid of japanese knotweed from my garden.

It grows up every year and so far I cut it down and injected ammonium sulfamate into the stem. This has worked well considering the amount of the area infected but it is still growing up through the grass. The ammonium sulfamate has of course distroyed a large part of the garden so using this technique across the whole garden isn't a good idea. The roots are quite big and strong so digging them up would be hard and again wreck the garden, plus there is no guarantee it will get rid of all the roots.

If I let it grow up then inject the AMS into the stem again, would this kill the new roots?

 

What a brute!
Thankfully I don't have that problem
http://www.dgsgardening.btinternet.co.uk/japknot.htm
Any help Andy?

 

I've not come across the problem personally, but in my local park they are trying to eradicate it.


Its a long process, they have not dug any roots out, (probably through fear of spreading it), they just treat it with weed killer every august.
After three years the new shoots are now very weak, but its not given up yet.

I dont know what chemical they use, but guess its some kind of professional strength material, not commonly available.

 

It usually takes around three years to eradicate knot weed, this is the industry standard time scale.

Regular spraying with glyphosate (roundup) is effective as are some of the professional use herbicides eg timbrel but all take time, both glyphosate and timbrel are more effective tank mixed with a cutting agent (mixtureB).

Digging up the roots is ineffective since they go down a significant depth and the roots and stems would have to be burnt or disposed of as contaminated waste. The transfer of soil or vegetation containing know tweed is illegal with heavy fines from the environment agency.

In other words its a long battle of persistence.

 

Excellent post Paul

 

We had some at a local piece of waste ground that some folks tried to convert into a public garden (not quite a park, being tiny) with funding from New Deal. We got a monthly newsletter about progress. Basically they sprayed it regularly (every couple of months) with a glyphosate based systemic weed killer. After a couple of years they brought in the mini diggers to get the bulk of the roots out.

From what I understand about invasive weeds, digging out the roots is not such a good idea, as you don't want to break them in case all that lovely glyphosate hasn't yet worked its way down to all the nooks and crannies. But then who am I to argue with the contractors that came along, so I couldn't possible say whether to dig it up or not.

 

Dealing with Japanese Knotweed is complicated. You cannot move ANY part of the plant from a contaminated area, if you want to burn any part of the plant you ( officially ) need a special permit. When I treat it, I spray every couple of weeks with Glyphosate, Even then, as Paul says, it takes several years. And that`s not gauranteed.

 

Whew bless us all and I thought I had weed problems:flag:

 

This sounds like the flipside of gravel and clay.

 

"... injected ammonium sulfamate into the stem"

An you still get ammonium sulfamate? I thought it had been banned :( I'd like some for my marestails

"The ammonium sulfamate has of course distroyed a large part of the garden"

Ah ... I think that ammonium sulfamate is selective and shouldn't kill anything other than what it has been sprayed on to. Could it be that you are using something else? Sodium chlorate perhaps? (No idea if that is effective against Knotweed, but it would certainly kill everything in the area it is applied!)