Japanese Knotweed

Essexboy

Help!
Does anyone know how to get rid of Japanese Knotweed permanently?
It has finally arrived in North Sligo (easily overlooked in hedges) and my garden.
From what I have read, burning, slashing etc. only work temporarily, then it returns, worse than ever.
Thanks.

smashey

Try the Gardening/DIY forum.

Slow Motion

Kill everything (weedkiller etc) and start from scratch is the only advice I can think of ! That stuff is worse than triffids.

nanook

moved

10-10-20

Have a look at 'treatment' http://www.co.clark.wa.us/weed/documents.html

Irish Gardener

Hello Essexboy
I see you've met our friend Japanese knotweed AKA Polygonum japonicum.
Its a weed that is very resistant to herbicides, roundup will usually work but it must be applied every year for 3 years.
Firstly, cut the weed to the ground in winter, then spray the regrowth in may and August.
Beware pulling the weed, you will just leave root tips in the ground which will grow back as strong as ever.

10-10-20

Any estimation on it's arrival in Dublin? Are we talking 5 years?

magicbastarder

you can make soup with it, it's that's any consolation.

10-10-20

You can make soup with nettles too, but I don't see many jumping to offer to take them away...

The Hill Billy

There was a letter in the Irish Times last week about this & IIRC one correspondent wrote in to say that it took him/her two years of injecting the plants (using a syringe) with Roundup to kill it. He/she said that it re-grew the second year, but not as strongly & after the same treatment it never grew back.

tampopo

10-10-20, it's IN Dublin, believe you me. I'll post more later.

Essexboy

Irish Gardener wrote:

Hello Essexboy
I see you've met our friend Japanese knotweed AKA Polygonum japonicum.
Its a weed that is very resistant to herbicides, roundup will usually work but it must be applied every year for 3 years.
Firstly, cut the weed to the ground in winter, then spray the regrowth in may and August.
Beware pulling the weed, you will just leave root tips in the ground which will grow back as strong as ever.

Thanks for the advice, Irish Gardener. Looks like Roundup is the answer.
I have already cut the plant back to its roots so when/if the rain stops, I will attack with Roundup.
Like your website, by the way.

Reyman

10-10-20 wrote:

Any estimation on it's arrival in Dublin? Are we talking 5 years?

It's in Dublin in a big way. Try walking along the Dodder banks near Milltown - lots of it there.

The Hill Billy

Essexboy wrote:

Thanks for the advice, Irish Gardener. Looks like Roundup is the answer.
I have already cut the plant back to its roots so when/if the rain stops, I will attack with Roundup.
Like your website, by the way.

The Roundup will be of limited use if there is no regrowth as it is primarily absored through the foliage. (I think )

Irish Gardener

Hill Billy wrote:

The Roundup will be of limited use if there is no regrowth as it is primarily absored through the foliage. (I think )

Don't worry, there will be leaf regrowth.
This is Japanese Knotweed we are talking about.

As Rick says in Casablanca....... ""Maybe not today. Maybe not tomorrow, but soon and for the rest of your life."

Of course I would try and avoid the "rest of your life" end of things.:)

tampopo

10-10-20,

I approached the National Parks and Wildlife Service over a year ago regarding infestations of JK. Here is what I got back.

Japanese Knotweed (Fallopia japonica) is an alien species. Under
Section 52(7)(c) of the Wildlife Act, 1976 (as amended) 'Any person who
plants or otherwise causes to grow in a wild state in any place in the
State any species of flora, or the flowers, roots, seeds or spores of
flora otherwise than under and in accordance with a licence granted in
that behalf by the Minister shall be guilty of an offence.

For the purposes of Section 52(7)(c) any reference to plants, flowers,
roots, seeds or spores refers only to exotic species.


Japanese Knotweed was first introduced to Ireland over 100 years ago
and forms dense thickets along roadsides, waste-grounds and waterways.
It reproduces by vegetative means and is difficult to kill off once it
becomes established. This plant is included among the list of the 100
most invasive alien species of the world.

The threat caused by Japanese knotweed is taken very seriously in
Ireland. It forms dense cover forcing native plant species to die off.
It also grows to heights of 2-3m and reduces visibility along roadsides
while also making access to sites difficult for walkers and anglers.

An all island report on Invasive Alien Species was commissioned by the
National Parks & Wildlife Service and the Environment and Heritage
Service (EHS), Northern Ireland and was published in 2005. This report
sets out a number of key actions to tackle the threat of Invasive Alien
Species on the island of Ireland. A contract was recently awarded to
Quercus to implement the recommendations set out in the report.

A central requirement when dealing with japanese knotweed is to ensure
that any viable rhizomes, the main means by which the plant spreads, are
not given the chance to escape into the wider environment. It is
recommended to spray the plant with a systemic herbicide prior to
transport, to ensure no material is lost en route, and finally that the
material is deeply buried in a properly managed landfill which has an
effective pest control management system which can deal with any
regrowth.

Another approach acceptable to NPWS is to spray the plant and then
carefully remove the soil layer containing all the rhizomes, they can
grow down to 2 metres below the surface, and store it permanently on
site and respray any regrowth as necessary over the next few years.

Useful references on the control of Japanese Knotweed are "Guidance for
the control of Invasive plants near watercourses" and R&D Note 233
"Control of Invasive Riparian and Aquatic Weeds" both of which are
available from the NRA (National Rivers Authority), UK.

If you wish to discuss the removal of a specific infestation you can
contact me at the number below and I can put you in touch with your
local NPWS conservation officer. I hope this answers your query.

Regards

Jamie Mulleady
Species and Regulations Unit
National Parks and Wildlife Service
01 - 888 3214
______________________________

As soon as I knew what I was looking for, I kept spotting it all over!
In Donnybrook at the bridge over the river Dodder, heading out of town, on the left hand side at the back of Wesley's clubhouse.
On the red Luas line, heading out of town at the back of St.James' Hospital, as you begin the long turn in to the Fatima station, at the base of the old granite wall there's one.
Along the border railings and James' Hospital and the Luas line between Rialto and Fatima stations.
To the rear of Stewart's Hospital swimming pool (Waterstone Park?)in Palmerston, there are many infestations.
West of the Garden of Remembrance in Islandbridge there are infestations.
162 Crumlin Rd. front garden (for 20-25 years)

I reported these locations to the chap in NPWS and he said he wasn't familiar with these places. He said he'd get a regional inspector to have a look at them. I called him back several months later and nothing had changed or moved on. The infestations are still there.
In summation, there is no political will to do a damn thing, despite all their protestations.

There were a couple of items on the Pat Kenny radio programme over the last six months. NUIG are doing a survey in Galway county only. I emailed them for advice but they said it was for Galway county only. I was in Clifden over the summer and spotted two infestations, one in Oughterard, just past the big church over the bridge about 200m, and on a roundabout in Galway city, the Kenmare Roundabout? I emailed them but got no acknowledgment.

The second one has a website...www.knotweedtogo.com but I haven't yet contacted them.

It's causing fierce delays and extra expense at the site for the London Olympics 2012, trying to eradicate it. It regrows from the tiniest little bit.

good luck essex boy, try burning it, but please don't put it in your bin.

Finnmac

10-10-20 wrote: »

Any estimation on it's arrival in Dublin? Are we talking 5 years?

Its well published that J. Knotweed was brought into Ireland by the Victorian gardeners. Now it is taking over, every where I go now I see it, I have mapped it from the Upper, Middle and Lower stretches of the River Dodder. Also as Tampopo observed in gardens around Dublin. I have a map where I record any sightings of Knotweed and Himalayan Balsam. The protected Booterstown March has established stands of Knotweed also Irishtown Nature Reserve. I am currently in my second year of treating knotweed with Roundup Biative in two South Dublin gardens. The method I use is cut and pour, low down at approx the second node of the stem. The cut stems I leave to dry in special secure containers I have, then when fully dried I burn the stems completely. I am not aware of any licensed land fill sites that you can dispose of Knotweed material. However I will be applying for a license from the NPWS in May 2015 to continue into the 3rd year of treatment programs controlling this highly invasive plant.

skh2

I have just noticed two infestations of knotwood on Rafter's Lane in Dublin 12 (number 1 and 2 - both vacant plots, one empty, one with a boarded up house). My garden backs onto the lane - do I need to be worried about invasion spreading across the road to my property?

I've already rung Dublin council and reported it to the parks division, they said they'll send out the regional parks manager for a look and "get on the case", whatever that means.

Be very grateful of any advise, as definitely don't want that stuff on my land!