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]

20 minutes ago, peds said:

Might just not bother and grow my tomatoes somewhere else!

If you're growing there it means you can monitor the weed, glyphosate will deal with all the aerial bits so it will not interfere with your tomato plants.

[Hoolio206]

 

I had a patch of knotweed probably  and area of 15Mx10m with 1-2M stems.   I bought an injection tool from the US from JK injection systems.  Then I injected the stems with neat glyphosate in late Summer.  It certainly worked as there were only 10% of stems the next year and I have kept hammering them every Summer for 5 years.  I get the odd stem popping up but nothing like what was there before.

My advice is keep monitoring the patch and keep injecting.  Maybe a large syringe would do the job, or an old sheep worming needle.

Hope you get rid of it.

[s o c]

2 hours ago, Hoolio206 said:

 

I had a patch of knotweed probably  and area of 15Mx10m with 1-2M stems.   I bought an injection tool from the US from JK injection systems.  Then I injected the stems with neat glyphosate in late Summer.  It certainly worked as there were only 10% of stems the next year and I have kept hammering them every Summer for 5 years.  I get the odd stem popping up but nothing like what was there before.

My advice is keep monitoring the patch and keep injecting.  Maybe a large syringe would do the job, or an old sheep worming needle.

Hope you get rid of it.

Safer (and faster)to use  proper injection tool.

fella I know almost got round up in his eyes when needle broke 

 

[peatff]

You can eat the fresh tips off the knotweed apparently it tastes like rhubarb. You have to cook and eat them on site though as it is an offence to move it. 

[Haironyourchest]

4 hours ago, peatff said:

You can eat the fresh tips off the knotweed apparently it tastes like rhubarb. You have to cook and eat them on site though as it is an offence to move it. 

Tried it - delicious! Better than rhubarb. The Japs make tea from it as well, supposably has health properties. 

[Gary Prentice]

On 12/04/2019 at 18:53, Hoolio206 said:

 

I had a patch of knotweed probably  and area of 15Mx10m with 1-2M stems.   I bought an injection tool from the US from JK injection systems.  Then I injected the stems with neat glyphosate in late Summer.  It certainly worked as there were only 10% of stems the next year and I have kept hammering them every Summer for 5 years.  I get the odd stem popping up but nothing like what was there before.

My advice is keep monitoring the patch and keep injecting.  Maybe a large syringe would do the job, or an old sheep worming needle.

Hope you get rid of it.

Five years of chemical application 

 

I really do wonder what the result would have been if you'd just cut new growth down every time it emerged for the same period of time. I just assume that any plant that isn't allowed to photosynthesis must eventually exhaust itself and run out of energy?

[Hoolio206]

Just checked the Knotweed patch for fresh growth and there were 2 stems which I have cut.  

Five years ago there were hundreds.  So it has worked.

[openspaceman]

2 hours ago, Hoolio206 said:

Just checked the Knotweed patch for fresh growth and there were 2 stems which I have cut.  

Five years ago there were hundreds.  So it has worked.

Back on page 3 I said I would check on a patch I pulled 20 years ago, I did and found no regrowth but wondered if I was still a bit early in the season. There were no standing dead stems  and plenty of nettles had taken their place.

[SteveW1000]

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

 

 

 

 

 

Head of parks in my borough told me the same however they also said they would still permit it's use for JK and Giant Hogweed which is a much bigger problem on one of the sites I work on.  Spraying will have a negative impact of insects however it seems that stem fill or injection will have little impact.  Last year knocked out 85% of the JK by injection when previous years spraying seems to have just kept it in check.

[Peasgood]

Persistence is the key to success whichever method you use. 

As soon as you ease off it gets a foothold again and you are back to square one. 

My personally preferred method is 50% glyphosate injected into the stems. I just use a big syringe from ag health supplies and a fat needle, sometimes drill a hole first if it is practical.