Anybody else here struggling with Japanese Knotweed?

my3cents

Kazbah wrote: »

Is there anything stronger than roundup available even with a license?

Nope nothing.

That's the problem its a bloody super weed!

Jap.knotweed

Needs to be injected with herbicide. Glyphosate based at this time of year. Used only aquatic approved like roundup 360

monkeynuz

Jap.knotweed wrote: »

Needs to be injected with herbicide. Glyphosate based at this time of year. Used only aquatic approved like roundup 360

Your advice will fall on deaf ears here, try reading the entire thread and you'll see I've already tried.

And ideally it should be roundup pro biactive.

Kazbah

monkeynuz wrote: »

Your advice will fall on deaf ears here, try reading the entire thread and you'll see I've already tried.

And ideally it should be roundup pro biactive.

What's the difference?

ithread

Hi all

When are people going to give that last spray this year? Our JK doesn't flower anymore so it is hard to guess when that right moment is??

Thanks

my3cents

ithread wrote: »

Hi all

When are people going to give that last spray this year? Our JK doesn't flower anymore so it is hard to guess when that right moment is??

Thanks

Weather is the big issue, no point planning a particular day or even week if it rains. So as I said earlier I spray from the end of August but anytime from now on (nearly first week in September) is good.

I sprayed one area last week and it rained that night so I'll give it another spray as soon as we look to be getting a dry day.

ithread

yes definitely not today anyway - wash out!

my3cents

Kazbah wrote: »

What's the difference?

Not much the bit that kills the JK is the same, there are loads of other chemicals that hold the formulation together and they are different. Biactive formulations are supposed to break down quicker. Clearance for aquatic use just means that the manufacturers have gone and got approval for that specific use again the glyphosate is still glyphosate when it comes to killing JK. If the JK you are spraying is by water then use a formulation with aquatic clearance. Maybe some of the surfactants in one mix are slightly better than another in holding the herbicide on the plant and aiding absorption but not that I've ever noticed.

monkeynuz

ithread wrote: »

yes definitely not today anyway - wash out!

Unless you're in the sunny southwest, no rain here!

Kazbah

I bought 5L of the Roundup Bioactive. The guy in the Coop said he'd recommend a 50:50 ratio. Is there an advantage to inject it? A gardener quoated be €150 to inject and spray?

monkeynuz

Kazbah wrote: »

I bought 5L of the Roundup Bioactive. The guy in the Coop said he'd recommend a 50:50 ratio. Is there an advantage to inject it? A gardener quoated be €150 to inject and spray?

That ratio is spot on for injecting personally and also what used to be recommended practice stem injection is the best in conjunction with spraying the leaves with a slightly weaker mix.

my3cents

Kazbah wrote: »

I bought 5L of the Roundup Bioactive. The guy in the Coop said he'd recommend a 50:50 ratio. Is there an advantage to inject it? A gardener quoated be €150 to inject and spray?

DO NOT USE A 50:50 MIX! Thats just a waste of spray and unnecessary polution, the guy working in the Coop is working in the Coop for a reason!

Read the thread there's info on the correct rate, over dosing is no better than underdosing.

Even if injecting 50:50 is far too strong.

Kazbah

I'm only going to spray it myself but do you think it's worth paying someone to inject it?

my3cents

Kazbah wrote: »

I'm only going to spray it myself but do you think it's worth paying someone to inject it?

iirc from the picture of the plants you posted the stems weren't really that thick so not ideal for injecting. If you want to get maximum effect then I did read a report somewhere recommending spraying again after 10-14 days, the leaves won't have been affected by the herbicide at that stage so can still take up more.

I'd like to know how someone is going to inject the stems as its not as easy as you think it is. The proper tool for doing the job would cost €400 or more (unless someone can find it cheaper?) so I doubt your average gardener will have one.

monkeynuz

my3cents wrote: »

iirc from the picture of the plants you posted the stems weren't really that thick so not ideal for injecting. If you want to get maximum effect then I did read a report somewhere recommending spraying again after 10-14 days, the leaves won't have been affected by the herbicide at that stage so can still take up more.

I'd like to know how someone is going to inject the stems as its not as easy as you think it is. The proper tool for doing the job would cost €400 or more (unless someone can find it cheaper?) so I doubt your average gardener will have one.

Cocktail stick and large syringe from vets or stem inject kits were available for £100+

And 50:50 is correct strength for stem injection.

celticbhoy27

Just reading this months edition of tge irish garden. Anybody else read it? Does a piece on an impressive garden each month. This month it has the usual impressive garden and one of its "features" is a JK tunnell

recedite

Looks like settled dry weather until next weekend.
Now's the time if you're gonna do it!

Markcheese

My neighbours JK is currently being swamped by their bind weed, briars and that wild clematis stuff !!
I better go borrow a sprayer to do my side of the ditch - a bit worried about throwing the balance out - :-)

recedite

Think you may need to Napalm that ditch.

Lucena

Markcheese wrote: »

My neighbours JK is currently being swamped by their bind weed, briars and that wild clematis stuff !!
I better go borrow a sprayer to do my side of the ditch - a bit worried about throwing the balance out - :-)

I've heard lots of anecdotal evidence that nettles and briars are quite effective at holding back JK. Not aware of anyone actually planting those plants to get rid of JK, though.

Markcheese

recedite wrote: »

Think you may need to Napalm that ditch.

Now where can I get a B1 and a full load of napalm- and maybe a side of agent orange - what could possibly go wrong . (I'm sure the first thing back would be the knot weed)

Kazbah

my3cents wrote: »

iirc from the picture of the plants you posted the stems weren't really that thick so not ideal for injecting. If you want to get maximum effect then I did read a report somewhere recommending spraying again after 10-14 days, the leaves won't have been affected by the herbicide at that stage so can still take up more.

I'd like to know how someone is going to inject the stems as its not as easy as you think it is. The proper tool for doing the job would cost €400 or more (unless someone can find it cheaper?) so I doubt your average gardener will have one.

Yeah I think the guy that came has the specialist equipment but I sprayed it myself during the week with 25ml per litre and I will do it again if the weather is dry 10-14 days after first spray. I don't really have the money to get it injected. I'll see how that goes then next April/May

my3cents

Kazbah wrote: »

Yeah I think the guy that came has the specialist equipment but I sprayed it myself during the week with 25ml per litre and I will do it again if the weather is dry 10-14 days after first spray. I don't really have the money to get it injected. I'll see how that goes then next April/May

I researched the injection equipment a few times and some of the manufacturers supply a small needle for injecting thin stemmed regrowth.

I'd love to do more injecting of JK but when faced with half an acre of it and no more than a couple of hours a month to devote to the problem it isn't going to work for me.

ithread

We sprayed our JK last Sunday before we went on holiday. Came back to find that it is definitely withering but lots of the leaves have just fallen off...should I pick these up? Are they dead? I'm afraid they will blow away and sprout new plants??

my3cents

ithread wrote: »

We sprayed our JK last Sunday before we went on holiday. Came back to find that it is definitely withering but lots of the leaves have just fallen off...should I pick these up? Are they dead? I'm afraid they will blow away and sprout new plants??

Leaves won't sprout new plants, you need any bit of the tuber (the roots) or a piece of the stem including the bud where the leaf was attached.

fits

We dealt with a small patch yesterday. 3x2m or so. Probably very late for this year. We cut the stems and carefully put them in old plastic coal bags and into a shed to dry and later burn. We injected the stems with gallup (50/50 dilution). The plants were tall but are competing with briars so not very vigourous. We are going to be doing work on the site now starting with some tree felling so im worried we will spread it around the site.

my3cents

fits wrote: »

We dealt with a small patch yesterday. 3x2m or so. Probably very late for this year. We cut the stems and carefully put them in old plastic coal bags and into a shed to dry and later burn. We injected the stems with gallup (50/50 dilution). The plants were tall but are competing with briars so not very vigourous. We are going to be doing work on the site now starting with some tree felling so im worried we will spread it around the site.

Thats a great way to get rid of the stems if you only have a small quantity.

If you aren't digging the soil up then you shouldn't spread it, hand cultivation is probably OK as you aren't moving the roots around much the real problem is when machinery starts pulling it about, some bits get burried and can come up a couple of years later.

taxusbaccata

Has anyone heard or tried using Lime and using heat?

I have read some USA forums where setting a large fire above the knapweed has been successful - ie the very hot soil for several hours kills the root.

Does knapweed like acidic soil? If so the lime strategy seems plausible.

my3cents

taxusbaccata wrote: »

Has anyone heard or tried using Lime and using heat?

I have read some USA forums where setting a large fire above the knapweed has been successful - ie the very hot soil for several hours kills the root.

Does knapweed like acidic soil? If so the lime strategy seems plausible.

At the depths the rhizomes go to I doubt heat would have any effect, I've had massive fires over tree stumps for days that only scorched an inch or so of the surface of the stump.

In general I would say a the majority of the sites I've seen Japanese knotweed on are acidic but I doubt lime is going to make any difference to established plants.

taxusbaccata

my3cents wrote: »

At the depths the rhizomes go to I doubt heat would have any effect, I've had massive fires over tree stumps for days that only scorched an inch or so of the surface of the stump.

In general I would say a the majority of the sites I've seen Japanese knotweed on are acidic but I doubt lime is going to make any difference to established plants.

Possibly so my3cents.

Your fires may have visually scorched an inch or so but the heat would transmit much deeper than that. Plants can be very sensitive to pH changes it would interesting to try it out.

It would seem we will all have great opportunities to try lime, heat or other methods as this alien isn't going anywhere.