Jap Knotweed...consience v 'walk away'.

[Haironyourchest]

I have a small area of JK at one of the entrance rides to my wood, it's in amongst a load of old soil/rubble that was dumped there way before we owned the wood and has only spread about 5m in the 13 or so yrs we've been here (and I left it cos blackcaps best in it every year)

It's now an issue as I'm selling a block of woodland adjacent to it and auctioneer has brought it up.

I've sprayed off the JK that's spread with glyphosate but just been told it's not effective (the 'infected' rubble area is being dragged onto adjacent concrete pad and torched with a load of straw and diesel)

Any suggestions for a more effective chemical treatment

 

 

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Glyphosate is effective if injected directly into the stem at the right time of growth and in the right concentration. Every single stem has to be treated. You could do this yourself if you buy the special injector (£400?) but it can be done painstakingly with a livestock syringe. It does work, but there will still be some life in the rhizome that will come back the following year, but the growth will be very stunted. This growth could be reinjected or just sprayed. My uncle had it done at vast expense and it worked well.

[agg221]

There was a small patch of it between us and our neighbours when we bought the place. Between us we have now nearly eradicated it - pulling any young growth every two weeks and shading it out by letting nettles and scrub grow over it to stop young shoots making it through has done the trick. It has taken about two years but not a lot of actual time (a few minutes every fortnight).

 

I haven't found it grows back from any of the pulled material - I spread it out in the sun and it seems to wilt off too much to recover within a day or so.

 

Alec

[timbernut]

Haironyerchest do you know what the mix is, I just used some left over from stump treatment (10%?), sprayed immediately after cutting. My son has just reminded me that there was another patch at other entrance but after cutting and regular foot/vehicle passage it just gave up. Probably helped by nettle cover as well like Alec said. Thanks for tips

 

 

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[Haironyourchest]

I can't remember the concentration, but a search would reveal it. I think spraying after cutting is maybe not going to work, as roundup is absorbed through the leaves and the plant has to be alive and circulating in order to carry the roundup to the roots. I believe when cut, the capillaries in the stem close up but I could be wrong. Cutting at full growth, then spraying the next growth is also said to be effective. There's a lot of energy stored in the rhyzome system, so the idea is to let the plant put that energy into growth, cut the growth before the plant can start storing energy again, and repeat, gradually depleting the energy stores till the plant gives up and dies. Can be done without chemicals, just takes vigilance and time.

[drinksloe]

Mus admit only had the 1 experience with it next to amates neighbour,

 

Some quite big patches, i cut most of the big stuff (actually found my pen knife was the easiest to keep stems intact) pierced the stem with some fencing wire (seemingly a membrane about groundlevel u have to burst) and just filled the stem up with a strong mix of glyco with a normal sprayer set on a single jet spray.

But some of the other areas esp smaller stems i just sprayed with strong glyco bout this time of year.

 

To be honest hardly any difference both have worked far better than i expected, if anything more regen in the patch i injected but that was also the patch with the biggest stems/plants so i imagine stronger.

 

By all accounts the trick is not to redisturb the soil as can ly dormont for up to 20 odd years.

So i'd just treat the surface but don't dig up the rubble will only makeit worse

[richy_B]

Spraying is effective. You just need to be patient. Tell them it has a management plan in place. Spray twice a year, 1st and 3rd week of September for the next 5 years.

[timbernut]

Thanks chaps,sprayed last w/end so will give another dose next week and see how it goes, I told agent management plan is in place

 

 

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[peatff]

There's some over the wall at the bottom of our garden and I sprayed it with glyphosate I think it was in May when it was in leaf starting to grow and it has only just started to show itself again so I am going to give it another dose now as it is about to start feeding the rhizomes for winter.

[Haironyourchest]

By the way, Jap knotweed shoots are edible - delicious tastes like mild rhubarb. My next door neighbour used to make crumble with it, and is still going strong. The Japanese make tea from the leaves.

[Gary Prentice]

Probably best to harvest leaves before spraying then?