Japanese Knotweed - how to kill?

my3cents

Mousewar wrote: »

So looks we have this in our estate here in Dublin. It's about 8ft tall already in a garden across from me and is now running along the wall on the common green area where it is about 5ft. There's a few other patches on it here and there as you go along.
I have two questions.
First, is there anything in particular I can do to ensure it doesn't come onto my property? My garden is about 7 or 8 metres from it.
Second, we have informed the council who say they'll be out. This would be dun laoghaire rathdown. Does anyone have experience with the council treating this? Basically I'm wondering can I trust them to do it properly or should I be thinking of taking matters into my own hands?

I'd get back to the council and ask them what their action plan is for treating JK. I suspect they are just doing one kill at the end of the season which is ideal however you are left wondering if they are going to remember for the next 3 months.

The chances are if they don't forget you (they shouldn't) then they will do a decent enough job a lot of councils are now using newer chemicals like Icade which from what I have seen do an excellent job. As I keep on being pulled up for saying while spraying late works best the crop can be so large that some areas get missed so one way or another you'll get regrowth next year unless you are very lucky. But with you monitoring it and getting on to the council and repeatedly reporting any regrowth over the next few years it should be eradicated.

The problem may be that the Council won't spray the garden in front of you if that is private property another reason to check with them on their policy for dealing with JK. If the council won't do that area then plenty of advice here already on what you can do.

I've done some small areas with Roundup in a 1litre spray bottle with good results (its easy to hide and I didn't want to wander around the beach with a big yellow 20litre Knapsack sprayer) so I know its not like you have to go buying a lot of expensive equipment to deal with it. A quick note about it growing on the beach, the bastard stuffs roots wash down rivers go out to sea and root again when they get washed up on the top of the beach - it really is tough stuff.

Mousewar

my3cents wrote: »

I'd get back to the council and ask them what their action plan is for treating JK.

Yeah I did ask when I called but you're just talking to some guy on a desk who doesn't know that stuff. He just said the lads who come out will know what they're doing.

my3cents wrote: »

The problem may be that the Council won't spray the garden in front of you if that is private property another reason to check with them on their policy for dealing with JK. If the council won't do that area then plenty of advice here already on what you can do.

Yeah that is my worry although it's clearly the same plant, just two sides on the wall. That house is rented and I get the impression they guy living there doesn't give a damn. I'll try to get onto the landlord.

Thanks for the advice.

Good loser

A smallish clump I sprayed with Grazon last year came again this year and last week I decided to pull it manually, which was surprisingly easy to do. All came up except one, the biggest clump, which I just broke down.
Underground there is a mass of peat like material - small or large depending on the mass overground. The outlying plants were singletons but centre ones had 4 to stalks.
Will go back with Grazon later in year.

TomOnBoard

Good loser wrote: »

A smallish clump I sprayed with Grazon last year came again this year and last week I decided to pull it manually, which was surprisingly easy to do. All came up except one, the biggest clump, which I just broke down.
Underground there is a mass of peat like material - small or large depending on the mass overground. The outlying plants were singletons but centre ones had 4 to stalks.
Will go back with Grazon later in year.

Totally in contravention of current best practice advice. Even tiny fragments can reproduce. Where did you put the pieces you 'broke down' and pulled out?

Mousewar

I noticed today that someone, a neighbor perhaps, pulled one of the stalks away, presumably it was starting to obstruct the pathway. I can't see any of it left in the ground. Will that one grow back this year or will it re-emerge next year. I'd prefer this summer so it can get sprayed with the rest.

TomOnBoard

Mousewar wrote: »

I noticed today that someone, a neighbor perhaps, pulled one of the stalks away, presumably it was starting to obstruct the pathway. I can't see any of it left in the ground. Will that one grow back this year or will it re-emerge next year. I'd prefer this summer so it can get sprayed with the rest.

Id be more concerned about where he put the bits he pulled away! A recipe for another infestation! When will we run adverts on bloody TV to tell ppl to not pull the stuff???

orm0nd

my3cents wrote: »

Ok so a professional gardener who has been dealing with Japanese Knotweed for the last 35 years is out of their depth and someone who goes to an information morning is an expert?

How many sites with Knotweed have you treated and how many have you eradicated it from?

I will state again spraying early in the year mid May being ideal so we are getting too late for that is good practice because it reduces the height of the crop when it comes to the main spray timing at the end of the growing season.

You are advising people to fail in their task by allowing the weed to get too big. How do you advise spraying a weed that is 3m high and so dense that you can't even fight your way into without a machete?

I am a qualified sprayer operator, fully registered and certificates to prove it.

I have been in discussion with 2 CC , and have attended courses organized by the 2 main companies supplying the chemical recommended .

you will never ever get a total kill spraying in may , end of discussion

I'm only 2 years attacking this menace and like you got very poor results first year because I didn't know the correct procedure ,

I havent inspected last year's sites closely yet but from a distance looks promising

Anyhow no more posts from me here ,

I may post pics later ( good or bad results I ll post them, but I wont be going near sites the until august)

orm0nd

Good loser wrote: »

A smallish clump I sprayed with Grazon last year came again this year and last week I decided to pull it manually, which was surprisingly easy to do. All came up except one, the biggest clump, which I just broke down.
Underground there is a mass of peat like material - small or large depending on the mass overground. The outlying plants were singletons but centre ones had 4 to stalks.
Will go back with Grazon later in year.

and next year and the year after

death1234567

Good loser wrote: »

A smallish clump I sprayed with Grazon last year came again this year and last week I decided to pull it manually, which was surprisingly easy to do.

And also spectacularly stupid. Enjoy its inevitable return.

TomOnBoard

death1234567 wrote: »

And also spectacularly stupid. Enjoy its inevitable return.

And get ready for another infestation wherever the pulled pieces were dumped!!!

TheBoyConor

<MOD SNIP>

Try not to post when you're annoyed. Take a moment to cool down first.

And what did you break down the rest with?

If any fragments, even the tiniest bit, got on your shoes or clothing it could start a whole new infestation if it got transferred to be soil.

Have you any idea what damage you may have caused?

I'd suggest you find whatever tool you used, wrap it well with plastic and burn it in a hot fire. And your clothes and shoes you were wearing that day, boil them for an hour or else burn.

You can't take the risk of contaminating another area, however small the risk is (and it's not a small risk, it's SERIOUS) because this stuff is hell.

If people keep doing stupid stuff like this the country will be absolutely destroyed in a few years.

Mousewar

TomOnBoard wrote: »

Id be more concerned about where he put the bits he pulled away! A recipe for another infestation! When will we run adverts on bloody TV to tell ppl to not pull the stuff???

Yeah I'll try to find out. In this situation, if it's lying in their brown bin, is there something they can or should do with it?

Also, again, does anyone know if those roots are likely to produce another growth this season now that they've been antagonised?

yosemitesam1

Mousewar wrote: »

Yeah I'll try to find out. In this situation, if it's lying in their brown bin, is there something they can or should do with it?

Also, again, does anyone know if those roots are likely to produce another growth this season now that they've been antagonised?

The danger is when you stress the plant early some of the root system will go dormant and can randomly start to regrow over a number of years. The dormant roots won't receive any herbicide if applied

49801

Curious how successful would a bonfire be for small to medium infestation?

TheBoyConor

Completely unsuccessful.

It will burn off the stalks no problem but it will leave the roots more or less untouched.

The sooner people stop trying out hare brained methods of dealing with JK and start using proper tried and proven methods then the better chance we have of keeping JK in check nationwide.

With any non-proven method of treatment of JK you have to take a precautionary approach and assume it will only make the infestation worse rather than better because every time you go near or touch JK you run a very real risk of unwittingly picking up some of the debris and spreading the infestation to a new area.

Unless you are spraying it in the proper manner you shouldn't even be approaching or touching the affected area.

******If you don't know what you are doing, don't do it and then call a competent professional to deal with it.******

Markcheese

Actually I did the bonfire thing... I sprayed the plants off with round up in autumn... And then bonfired the stalks and stools in early spring, then resprayed the regrowth summer and and autumn... Seemed to do well...but it was a reasonably small patch.. Mostly on my former neighbours side of the ditch...

feartuath

Roundup in September worked for me
98% success rate in the few patches I have.
Unfortunately it is on both banks of the local stream and spreading every year.

patsy_mccabe

It just goes to show how delicately balanced our ecosystem is. What is it, only a shrub from another country?

Nekarsulm

In the very centre of Cavan town today.
This clump got beaten down into the river the other night In the wind.
I set out to spray it several times last Autumn, but it was always raining.
Council oblivious to it, despite emails pointing out all the growths around town.

I'll spray it this autumn no matter what.

my3cents

Nekarsulm wrote: »

9In the very centre of Cavan town today.
This clump got beaten down inti the river the other night In the wind.
I set out to spray it several times last Autumn, but it was always raining.
Council oblivious to it, despite emails pointing out all the growths around town.

I'll spray it this autumn no matter what.

...

If you can be bothered getting on to them again point out that they are causing it to spread leaving it to grow in the river like that.

Farmer

That's mad. You'd wonder how it got there in the first place if it doesen't seed. Shows how dangerous it is. Next thing it'll be in the river breaking up to land on some lake shore. I think I'd send them an email (paper trail) and copy it to Parks and Widlife

TomOnBoard

Farmer wrote: »

That's mad. You'd wonder how it got there in the first place if it doesen't seed. Shows how dangerous it is. Next thing it'll be in the river breaking up to land on some lake shore. I think I'd send them an email (paper trail) and copy it to Parks and Widlife

Criminal neglect on the part of the Council!! Jeez, that annoys me.. And every tiny piece that might have broken off will have gone downstream and is propagating itself by now. Disgraceful neglect by them..

Nekarsulm

Farmer wrote: »

That's mad. You'd wonder how it got there in the first place if it doesen't seed. Shows how dangerous it is. Next thing it'll be in the river breaking up to land on some lake shore. I think I'd send them an email (paper trail) and copy it to Parks and Widlife

The river would be much higher in winter, so I suppose a piece floated down some time and rooted.

If you are getting on to them, that's the Kinnypottle river, along the Bridge Street car park.
Huge infestation up stream 200 yards away at the gates of The Royal School.

Despite their official website having contact details where you can report J.K. They don't do anything.

The twits would probably send a team out to cut it away if you contact them at the moment .......

TomOnBoard

I'd be taking photos of all of it and speak with local newspaper(s).

This is really serious and local authority complacency is simply outrageous!!

Also contact local fishing clubs to get support..

Good loser

TomOnBoard wrote: »

Id be more concerned about where he put the bits he pulled away! A recipe for another infestation! When will we run adverts on bloody TV to tell ppl to not pull the stuff???

Left them where they were, just pulled them out of the ground. Roots have dried in the air.


People losing the run of themselves about this plant. I notice it takes years to spread any distance - except where Co Co intervenes.

TomOnBoard

Good loser wrote: »

Left them where they were, just pulled them out of the ground. Roots have dried in the air.


People losing the run of themselves about this plant. I notice it takes years to spread any distance - except where Co Co intervenes.

Jesus wept!!!

DX85

This post has been deleted.

blue5000

DX85 wrote: »

This post has been deleted.

Photograph it and email it to the coco.

patsy_mccabe

When you think aout it, hedge cutting by contractors will spread it like wildfire. Even when they move to a new location, they will be carrying fragments with them on the cutter.

waxmoth

Japanese Knotweed is naturalised and the current policy of trying to control by spraying is futile and causing much more environmental damage than the plant itself.
It really only thrives in disturbed ground and does not compete well when shaded - one method of containing it is to put down a ground cover fabric and plant willow through it.

On the plus side it is a very good late season source of nectar for insects and the root is the main commercial source of resveratrol which retails here at around € 2700/Kg.

blue5000

Thanks waxmoth but I prefer to get mine from red wine;)
https://www.quackwatch.org/01QuackeryRelatedTopics/DSH/resveratrol.html

patsy_mccabe

waxmoth wrote: »

..... On the plus side it is a very good late season source of nectar for insects and the root is the main commercial source of resveratrol which retails here at around € 2700/Kg.

€2700/kg....How does it spread? :cool:

Nekarsulm

waxmoth wrote: »

Japanese Knotweed is naturalised and the current policy of trying to control by spraying is futile and causing much more environmental damage than the plant itself.
It really only thrives in disturbed ground and does not compete well when shaded - one method of containing it is to put down a ground cover fabric and plant willow through it.

On the plus side it is a very good late season source of nectar for insects and the root is the main commercial source of resveratrol which retails here at around € 2700/Kg.

Have you planted any yourself?
In your garden perhaps, along the wall of your house?

Wouldn't think so.

It's still controllable up in our area anyway, the recession came just in time.
The halt in building and groundworks stalled a lot of its colonization.

my3cents

waxmoth wrote: »

Japanese Knotweed is naturalised and the current policy of trying to control by spraying is futile and causing much more environmental damage than the plant itself.
It really only thrives in disturbed ground and does not compete well when shaded - one method of containing it is to put down a ground cover fabric and plant willow through it.

On the plus side it is a very good late season source of nectar for insects and the root is the main commercial source of resveratrol which retails here at around € 2700/Kg.

The spraying doesn't cause much if any environmental damage because just about nothing in this country is adapted to live under Japanese Knotweed.

Spraying JK doesn't damage endangered wild flowers for example because the JK has already wiped them out.

ted1

patsy_mccabe wrote: »

It just goes to show how delicately balanced our ecosystem is. What is it, only a shrub from another country?

In its home country it grows on the side of volcanoesin hostile ground so it curtailed. In rich soil it flourishes

Mousewar

In our estate I've established that the problem is the owner of the house (he's not the occupier). It was him that came along one day and just yanked out one of the stalks despite knowing exactly what it was. He also said he's seen the stuff before and sprayed it last year but as he had no idea about the Aug/Sept rule I doubt he sprayed at the right time. The council are due out in August - I've spread the word to leave it completely alone until then. Hopefully they'll listen.

waxmoth

my3cents wrote: »

The spraying doesn't cause much if any environmental damage because just about nothing in this country is adapted to live under Japanese Knotweed.

Spraying JK doesn't damage endangered wild flowers for example because the JK has already wiped them out.

There will be environmental damage directly and from residues and runoff if the intention is to control all roadside stands this way. As it is not effective, and the complete stand may not be sprayed, continuous treatments will be required and the area will be increasing all the time.

ted1 wrote: »

In its home country it grows on the side of volcanoesin hostile ground so it curtailed. In rich soil it flourishes

And apparently the saying there is "Knotweed outlives the gardener and the garden"

TheBoyConor

patsy_mccabe wrote: »

€2700/kg....How does it spread? :cool:

well unless commercial enterprises set up to exploit the knotweed for the profit in it's roots then it doesn't make much difference what is in them.

It's a scourge.

Slightly off topic but I was up the Vee on the knockmealdown mountains recently as have family up that way and I see that rhododendron is running through the area like wildfire. It's been there many many years and has a whole mountainside covered and any native ecology is absolutely wiped out. Nothing can survive in a rhodo area except rhodo becuase it is so dense and there;s something secreted by it's roots that sterilises the soil.
But now I'm seeing it pop up in areas that were previously free.

It is another absolute travesty that will destroy our countryside and no-one seems to give a crap or do anything about it. Even in the national park in Killarney there is only a half arse effort made to control it.

They should get the army out to do work to control it and beat it. At least that way the army would be doing something useful rather than sitting on their holes in barracks.

Farmer

+1 on the rhodo.
It needs a national programme and an education plan as well. (Many people think they're lovely and why would you dig them up!)

It's very difficult to control especially if the seeds are blowing into you from an area that you have no control over

Purple Mountain

Sorry for the ignorance but why is it so bad?

Wanderer78

Purple Mountain wrote:

Sorry for the ignorance but why is it so bad?

It's an evasive species, that kills off native species, and grows at an astonishing rate

my3cents

Purple Mountain wrote: »

Sorry for the ignorance but why is it so bad?

It propagates easily and once established takes over an area creating an ecological desert where nothing else can grow in its shade.

Control is difficult takes a long time and is very expensive.

Nekarsulm

Another problem with Rhododendrum is that while it has a mass of flowers that bees love, honey made from them is poisonous to the bees.
So when they use the honey food stocks in the winter it poisons them.
You have to dig Rhododendrum up with a digger, its trunks are twisted and convoluted and not suitable to machine harvesting.
Good firewood when seasoned, however.

my3cents

Nekarsulm wrote: »

Another problem with Rhododendrum is that while it has a mass of flowers that bees love, honey made from them is poisonous to the bees.
So when they use the honey food stocks in the winter it poisons them.
You have to dig Rhododendrum up with a digger, its trunks are twisted and convoluted and not suitable to machine harvesting.
Good firewood when seasoned, however.

The digger can be part of the problem with Rhododendron Ponticum. Yes the stumps need digging up but if the branches haven't been cleared first then they get tracked in by the heavy machinery movement and take root creating new plants.

Thud

Nekarsulm wrote: »

Another problem with Rhododendrum is that while it has a mass of flowers that bees love, honey made from them is poisonous to the bees.
So when they use the honey food stocks in the winter it poisons them.

https://www.zmescience.com/other/feature-post/mad-honey-deli-bal/

eoinmk2

after finding a patch in the grandfathers garden. disaster, but caught it early.

after spraying what should you do with the dead material? leave it where it is, remove it (cut it off without disturbing the soil), burn it?

Bass Reeves

eoinmk2 wrote: »

after finding a patch in the grandfathers garden. disaster, but caught it early.

after spraying what should you do with the dead material? leave it where it is, remove it (cut it off without disturbing the soil), burn it?

All the advice here is to leave it and watch for regrowths.

Mousewar

The council are saying now they're coming out to do an initial spray of the knotweed in the coming days before treating it extensively in Aug/Sept.
Is that...is that a good thing?

In other news, on the dart at killiney I can see Giant Hogweed growing - looks about 12 foot or so.

my3cents

Mousewar wrote: »

The council are saying now they're coming out to do an initial spray of the knotweed in the coming days before treating it extensively in Aug/Sept.
Is that...is that a good thing?

In other news, on the dart at killiney I can see Giant Hogweed growing - looks about 12 foot or so.

I think coming out now is a bit late I like to get an early spray before the plants get to full size (in May) and to keep them down so they recover a bit before September but aren't as tall as they would normally be.

At this stage the plants are full size and may not all recover fully to get a good dose in at the end of the season.

However just the fact the council is coming out even if it is at a less than ideal time does have some good points.

Firstly they will know where the plants are when it comes to spraying later and will probably find a few more stands of it that aren't on their lists. Secondly it does show they are doing something and anything is better than nothing. Thirdly they may not have enough trained operators to get around to all the outbreaks they have at the best time so will cover more if they start early.

Edit> Also we have no idea what herbicide they council are using. Roundup is the one where the recommendation is for the spray at the end of the season before it dies down others such as Icade are recommended for use earlier in the year. A long read but some very good info https://www.property-care.org/wp-content/uploads/2016/11/PCA-Invasive-Weed-Conference-2016_Dr-Daniel-Jones-presentation.pdf .

Mousewar

Well, the owner of the property across from me showed up last evening and took a hedge trimmer to it. He'd done basically all of it before I saw him and intervened. He had been sent all the info on it and chose to ignore it and take care of it himself. I at least stopped him from taking the cuttings to the dump and have asked the council to intervene.