Japanese Knotweed ?

Usjes

Hi,

My mother got a gardener in to do the garden and he told her that she had JK. It's growing only 10 feet from the house and about 5 feet from her neighbour's extension. So I did a bit of googling and I'm almost certain its not JK. While it does have some cosmetic similarities, the flowers look the wrong size, the stalks are the wrong shape and colour etc. But all of these are subjective so I was looking for something which would prove for certain that it can't be JK. So reading about JK it seems that there are only female plants in the UK and Ireland so it only spreads via cuttings or root fragments. The plant in her garden currently has bunches of purple/black berries up to 1cm in diameter. Is this the definitive proof ? Or can JK have berries on it ?

Thanks,

Usjes.

Water John

Haven't seen berries on ours, must check. Like you, think its JK. See the residents of Glounthaune in Cork got special needles to inject weed killer into it. Cost about €300.
Best way to get rid of it.

my3cents

Some of the best simple guides are

Japanese knotweed http://www.fisheriesireland.ie/invasive-species-1/242-japanese-knotweed-id-sheet-1
Himalayan knotweed http://www.fisheriesireland.ie/invasive-species-1/241-himalayan-knotweed-id-sheet-1
Giant knotweed http://www.fisheriesireland.ie/invasive-species-1/239-giant-knotweed-id-sheet-1
Hybrid knotweed http://www.fisheriesireland.ie/invasive-species-1/237-bohemian-knotweed-id-sheet-1

Three spp and a hybid the fist one Japanese Knotweed, Fallopia japonica is the main one causing the weed problem but the others are around.

lazybones32

Usjes wrote: »

Hi,

My mother got a gardener in to do the garden and he told her that she had JK. It's growing only 10 feet from the house and about 5 feet from her neighbour's extension. So I did a bit of googling and I'm almost certain its not JK. While it does have some cosmetic similarities, the flowers look the wrong size, the stalks are the wrong shape and colour etc. But all of these are subjective so I was looking for something which would prove for certain that it can't be JK. So reading about JK it seems that there are only female plants in the UK and Ireland so it only spreads via cuttings or root fragments. The plant in her garden currently has bunches of purple/black berries up to 1cm in diameter. Is this the definitive proof ? Or can JK have berries on it ?

Thanks,

Usjes.

The purple 'berries' make it sound like leycesteria formosa

Water John

3cents, good pics there. Bit confused, I'd say mine is No 1 but the flowers are largely pink. Maybe that is acid soil?
No fruit

my3cents

Water John wrote: »

3cents, good pics there. Bit confused, I'd say mine is No 1 but the flowers are largely pink. Maybe that is acid soil?
No fruit

I've seen a lot of Japanese knotweed and tbh I don't think I've ever noticed pink flowers White/creamy is how I'd describe Japanese knotweed.

Japanese knotweed is all female in Ireland all from a single plant (a clone) so no fertile seed which is a good thing the other species I think can set viable seed here?

Fallopia japonica is a member of the Polygonum family (knotweeds) and I'm fairly sure there are some with pink flowers one that springs to mind is Persicaria Orientale which is a tiny bit similar but its an annual.

Another old name for Japanese knotweed is Polygonum cuspidatum.

Leaf sizes and dimensions are fairly consistent so measuring a few mature leaves can narrow down which is which.

Water John

Thanks, that might be it. It dies back totally every year.

Genghis Cant

my3cents wrote: »

Leaf sizes and dimensions are fairly consistent so measuring a few mature leaves can narrow down which is which.

Just on this topic. Be careful as there's also Giant Knotweed and Bohemian Knotweed which is a cross between Giant and Japanese.
So leaf size may not be a good guide.

This time of the year Japanese Knotweed is in flower and it leaves it easier to identify. Though if it's being treated with sprays it may suppress flowering.
It's a nasty dose this knotweed.

my3cents

Genghis Cant wrote: »

Just on this topic. Be careful as there's also Giant Knotweed and Bohemian Knotweed which is a cross between Giant and Japanese.
So leaf size may not be a good guide.

This time of the year Japanese Knotweed is in flower and it leaves it easier to identify. Though if it's being treated with sprays it may suppress flowering.
It's a nasty dose this knotweed.

No its ideal, I was suggesting that it was a good way to distinguish between the 4 types of Japanese knotweed.

There is a good side by side comparison here http://www.japaneseknotweedireland.ie/invasive-species/japanese-knotweed-knotweed and the pdf's I linked to above have similar comparisons and sizes.

I find JK easiest to identify from a distance of about 100m or more, there is nothing I know native to Ireland that has quite that same green colour that sort of glows (smugly) in comparison to other plants around it.

Now is the time to treat JK with as much ghphosate as you can get on it. When the leaves drop off later the plant takes all the available nutrients from the leaves down into the root system and the glyphosate goes with them making for a better kill.

Genghis Cant

my3cents wrote: »

No its ideal, I was suggesting that it was a good way to distinguish between the 4 types of Japanese knotweed. s

Ok. I missed that bit in your post. Where you mentioned it being a good way to distinguish between the different types of knotweed.

my3cents

Genghis Cant wrote: »

Ok. I missed that bit in your post. Where you mentioned it being a good way to distinguish between the different types of knotweed.

It didn't read very well and its a bit of a stretch to expect you to have opened all 4 links and downloaded all 4 pdf guides to see what I was on about.

Genghis Cant

my3cents wrote: »

It didn't read very well and its a bit of a stretch to expect you to have opened all 4 links and downloaded all 4 pdf guides to see what I was on about.

I didn't open any of them. I have plenty of literature here about knotweed, I'm very familiar with it. I just missed the bit in your post.

Unfortunately we've lost the war on knotweed. I think we're over ten years late. I see it exploding along river corridors as well as roadside verges.

There's still not near enough being done to control it.

Nekarsulm

There is a clump of it along a boreen I use. Been growing three years now. Instead of running after the Council and hoping they take action, should I hit it with a strong solution of Round-up myself?
Its in flower now, and only covers the area of a kitchen table yet.
Or is there something better to spray on it?
Even if it just checks it for this year.

Water John

Good time to spray it Nekar as it will take it down to the roots as it dies back as some one posted earlier.

Nekarsulm

Cheers!
Just noticed a whole other thread about it.
Is injecting each stem with 20ml of Roundup Bi-active at a 1:1 strength before spraying still best practice?
A sheep vaccination auto injector would be ideal for the job, i think.

my3cents

Nekarsulm wrote: »

There is a clump of it along a boreen I use. Been growing three years now. Instead of running after the Council and hoping they take action, should I hit it with a strong solution of Round-up myself?
Its in flower now, and only covers the area of a kitchen table yet.
Or is there something better to spray on it?
Even if it just checks it for this year.

I spray it fully aware that what I am doing is in effect illegal.

Still I would't want to stop anyone

For me to tell you to use a strong solution of Roundup would also be technically illegal. Read the label However you will need to use the stronger rates and wet as much of the foliage as possible to get the best effect.

The councils do however seem to have recently taken on board that they have some responsibility for controlling Japanese knotweed so if informed they may do something.

Water John

I think the injecting is in place of spraying. Don't think you have to inject each stalk as you'll find a whole lot go back to the one root?
The injector costs €300.

my3cents

Nekarsulm wrote: »

Cheers!
Just noticed a whole other thread about it.
Is injecting each stem with 20ml of Roundup Bi-active at a 1:1 strength before spraying still best practice?
A sheep vaccination auto injector would be ideal for the job, i think.

I'd disagree on the rate I use a lower strength but that will work very well. I'd be a little concerned if the sheep vaccination auto injector was ever used on sheep again? I use a metal wire to make a whole in the stem then a syringe like thing used in cooking to inject/tenderise meat - again an off label use Edit> This is what I use a Kitchen Craft Flavour Injector - £1.99.

For small isolated clumps injecting really is the way to go and can get a 100% kill if you get enough stems and are just a bit lucky (depends I think on how established the underground parts of the plant are).

Day Lewin

Nekarsulm wrote: »

There is a clump of it along a boreen I use. Been growing three years now. Instead of running after the Council and hoping they take action, should I hit it with a strong solution of Round-up myself?
Its in flower now, and only covers the area of a kitchen table yet.
Or is there something better to spray on it?
Even if it just checks it for this year.

Yes: probably the most sensible thing you could do.
Watch the place and re-spray when it reappears (it will)
Best way to control a small clump, much quicker than waiting for someone "official" to get around to it.

Nekarsulm

Well I wont be spending 300 notes for an injector for a clump on the public road, anyway

Something like this would be my plan....



They are given away by some chemical companies with the vaccination, so no problem getting rid of it after week killer used.

Or i'll just use the knapsack. Two minutes will treat it, hop out of the jeep, spray, and gone ....

Nekarsulm

Biggest risk of the injector would be getting into a rhythm of "Grab stalk, stab, squeeze trigger" over and over again. Till you inject yourself with round-up ....

my3cents

Nekarsulm wrote: »

Well I wont be spending 300 notes for an injector for a clump on the public road, anyway

Something like this would be my plan....



They are given away bysome chemical companies with the vaccination, so no problem getting rid of it after week killer used.

To save you some grief I'll tell you now the needle will get blocked very quickly so use a bit of wire to punch a hole in the stem first, cocktail sticks and toothpicks will also do the job.

I go for the first decent sized section of stem (it is hollow and compartmentalised like bamboo) a couple up from the base. I them make a hole in the middle and inject about 20ml into the hole.

the goon

Would I be right in saying the attached pic is Japanese knotweed? Spotted in Cork city. It looks like it has been cut back,which, I thought was not a good idea with this stuff?

Water John

Yeah, should not be cut. Glounthaune parish found 80 locations.

Usjes

lazybones32 wrote: »

The purple 'berries' make it sound like leycesteria formosa

Thanks lazybones, there are a lot of replies in the thread but yours is the only one that actually came close to addressing my question; Can JK have berries ???
The above pictute is the plant in question and I had already decided its most likely identity was 'Himalayan Honeysuckle', still given that JK is such a harmful plant, it would be nice to have a difinitive way of ruling out Jk. ie. that it is not possibe for JK to produce berrries (in this country any rate).

Water John

Don't know about it fruiting, but the leaf there doesn't look like JK.

my3cents

Usjes wrote: »

Thanks lazybones, there are a lot of replies in the thread but yours is the only one that actually came close to addressing my question; Can JK have berries ???
The above pictute is the plant in question and I had already decided its most likely identity was 'Himalayan Honeysuckle', still given that JK is such a harmful plant, it would be nice to have a difinitive way of ruling out Jk. ie. that it is not possibe for JK to produce berrries (in this country any rate).

No berries the three winged seeds hang down in racemes, but I have never noticed them, maybe because the plants are all female and there are no male plants in Ireland.

https://extension.umass.edu/landscape/weeds/polygonum-cuspidatum has a good picture of the seeds, note Ploygonum cuspidatum is an old name for what is now called Fallopoia japonic - Japanese knotweed.

the goon

Water John wrote: »

Yeah, should not be cut. Glounthaune parish found 80 locations.

Wow, can't believe there is such a disregard for the impact of this stuff. I know resources are always an issue but not addressing this now can only have negative and harmful repercussions long term

Nekarsulm

http://cavancoco.ie/invasive-species.htm

my3cents

Nekarsulm wrote: »

http://cavancoco.ie/invasive-species.htm

Think all/most of the coco's have some info online now I've been quoting cork coco's pdf on JK for a few years now http://www.corkcoco.ie/co/pdf/786446050.pdf .

Achasanai

the goon wrote: »

Wow, can't believe there is such a disregard for the impact of this stuff. I know resources are always an issue but not addressing this now can only have negative and harmful repercussions long term

I would imagine ignorance plays a large part in it too. The average person who sees this growing somewhere on their property or on a road side probably thinks they're doing a good deed in trimming it down, but just isn't aware that they are doing so much harm.

The other side of the issue is the lack of a nationwide plan to deal with it. Nekarsulm posted a link to (I think) Cavan Co Co where there is a clear method of reporting knotweed growth (whether anything is actually done about it is another matter) but I have found it quite difficult to find who to report sightings in Dublin. I found a place to fire off a form, but no idea who it's going to or whether anything will be done about it.