Japanese Knotweed

[peds]

Yeah I know, knot exactly a tree, but you guys are just so bloody clever I know you can help with this.

 

I've just inherited the use of a polytunnel which has lain dormant for a couple of years, and a nearby clump of Japanese Knotweed has started to poke through the ground in places. It's not too bad, but the problem will only get worse, obviously. I'll try and get a couple of photos tomorrow.

I've got plans to move the tunnel in the future, maybe next season, maybe the year after... but for this year, what can I do to minimise the problem? I'm wary of cutting the stems out, but I'd much rather keep the ground that I have available instead of putting in raised beds or benches after putting down sheets or slabs or something, as I hope to move the tunnel in the future. How much of an extra problem am I creating by just cutting the stems now and pretending they don't exist for the rest of the season?

 

Thanks for any advice dudes.

[openspaceman]

10 hours ago, Gary Prentice said:

I don't think that burning is particularly effective, as it originates from volcanic regions. Anecdotally a friend dug some of the roots up, threw them on his huge Nov 5th fire, only to discover new stems appearing at his fire site the following year, despite there never having previously been any JK in that part of the garden previously. 

 Well I suggest his fire just didn't get hot enough. Never transport it offsite to deal with it.

 

The idea is to get all parts above 90C  to kill.

 

Dry superheated steam sterilisation has been used in hot houses for years to kill off persistent pests. Thermal input need not be as bad as you think, especially if the soil to be treated is dug up and put through the treatment plant, in situ is an interesting challenge which I never got to try.

 

I was never certificated to work on site for JKW eradication but I did witness how poor and slapdash our operatives were so lack of effectiveness was not surprising (similarly I was "clerk of works" on the firm's rebuilding project and saw how poorly insulation details were complied with as BigJ mentioned in another thread) . Workers need to be competent and committed.

 

At the personal level I managed to pull up a clump on our local common 20 years ago and left the arisings to dry out, it appeared to kill the plant out, Woodworks says similar, I'll have to go back and see if it has reappeared.

 

It will never be easy and take a few seasons if it is an established infestation, whatever method is chosen, and yes I would start with glyphosate mid summer onward.

[Khriss]

This whole GM and Glyphosate business is cobblers as regards human health. It has a far bigger impact on wildlife than us and that should be the focus.

Oh an if yr into yr Organics, yup no proven case of GM food killing any one but oh.....!

https://www.forbes.com/sites/williampentland/2011/05/30/deadly-cucumbers-kill-14-in-germany-death-toll-still-rising/

 

Lethal cucumbers ! Nien! K

[Conor Wright]

13 hours ago, nepia said:

Many years ago I worked on arable farms and I've never heard that one.  Roundup on rape yes, but never wheat, barley or oats.  Am I just behind the times?

 

As for eating glyphosate you may be ingesting (allegedly harmless) breakdown products but you won't be eating glyphosate.  That's a bit like saying you'd be eating fungicide because Farmer sprayed the growing crop against Wilt.

It was practised for some years to "speed up ripening" faster ripening varieties have reduced the need for it and it's been restricted in the last number of years, banned in Austria and may well be banned here too in the coming years. 

Edited April 8, 2019 by Conor Wright
Correcting inaccuracies.

[Conor Wright]

I'd try flame weeding if you're totally against using chemicals. Salt may work but it will probably come back again.. it's incredibly persistent. Expose the rhizomes as much as you can without chopping them up, they like that the little bast.. anyway, we used, and still use flame weeders on my brothers farm. Virtually eradicated a serious dock problem, helps sterilise the soil too, so when you plant there are less critters to nibble your seedlings.. also when you introduce beneficial bacteria and nematodes etc theres less there to attack, eat or compete with them.

 

For your needs a camping gas bottle and gas torch should do.

 

If being wholly organic doesn't matter, glyhosphate is the best option, grow a green manure there for a year after if you're concerned about consuming food straight after chemical application.

[openspaceman]

8 hours ago, Conor Wright said:

it's a banned practise in these parts now

Where is that?

[Stere]

Some councils are going to stop using  glyphosate:

 

 

https://www.theguardian.com/society/2019/apr/05/uk-councils-weedkiller-cancer-link-monsanto-roundup

 

 

 

 

 

[peatff]

On 07/04/2019 at 22:50, openspaceman said:

How big an area?

 

You could dig it up, sift it out and burn it, just make sure you don't move any bits off the affected area. Soil sterilisation with steam is also a method.

You could be digging down to 2 metres and an area up to 7 metres bigger than the original patch though, knotted is not easy to eradicate organically. 

[Khriss]

On 09/04/2019 at 08:26, Stere said:

Some councils are going to stop using  glyphosate:

 

 

https://www.theguardian.com/society/2019/apr/05/uk-councils-weedkiller-cancer-link-monsanto-roundup

 

 

 

 

 

Anything to save money n make some redundancies ! K

[openspaceman]

11 hours ago, peatff said:

You could be digging down to 2 metres and an area up to 7 metres bigger than the original patch though, knotted is not easy to eradicate organically. 

yes that's already a given understanding and it will be highly dependant on how long the infestation has been established and the type of soil. As I said it had to be excavated to 4m and reburied in a plastic lined cell below this at Olympic Park.

 

One of the things about JKW is the way it reacts to a systemic herbicide like glyphosate. The rhizome that  stores its energy resources is sheathed in meristematic material, this is like our stem cells in that it is undifferentiated so can form any organ. The shoots are differentiated and cannot change, so they absorb the chemical via the leaves and translocate it to the rhizome. Only a limited amount of chemical gets to the rhizome and it only kills the meristematic tissue in a small area around it. If it hasn't killed enough to finish all the rhizome then the unaffected meristematic material is available to form new shoots, if triggered. In some situations this means it becomes next to impossible to kill the whole underground plant completely. Of course you never know if you have succeeded unless you observe it for the next few decades.

 

Bracken is similar in this respect.

 

 

[peds]

10 hours ago, openspaceman said:

 In some situations this means it becomes next to impossible to kill the whole underground plant completely. Of course you never know if you have succeeded unless you observe it for the next few decades.
 

Well, what a pisser.

 

Might just not bother and grow my tomatoes somewhere else!