Japanese Knotweed.....has anyone had success?

We have been offered to purchase a small piece of land, (approx 1/2 acre) adjoining our land here in Ireland.
It is very tempting...a beautiful old barn is on the land just ripe for renovation!
However...approx a quarter of the land contains Japanese knotweed which is uncommon in this area.

Could anyone advise if they have had success in removing it and if so, how they did so.

As you can imagine, I have read lots of suggestions....strim it down / keep pulling it up etc...(what every week!)
I would really like to know if anyone has had success in permanently eradicating it.
Advice most welcome
Sue

Oh, let me know when you find out! I have a path of it that is easily 30 feet in diameter that is threatening to grow over my barn. A gift from the previous owner. I think you will have to use some form of herbicide...

Don't try to dig them out and don't try to burn them. That's from personal experience.

I didn't have all that many so I cut them down a few times throughout the course of the growing season and just kept it up. My guess is I had somewhere around 100 plants. They have a longer growing season than the species that are indigenous to this area so I hit up the regrowth in late fall with a product called Rodeo. The plants they were competing with were dormant by then so it was easy to knock them back chemically at that time of year without negatively affecting desirable species. I think I am rid of the Polygonum cuspidatum (now known as Fallopia japonica) right now but I do check the area where they were frequently.

You could probably smother them quite effectively.

These plants are not all that hard to destroy. You just need to keep up the pace.

Other ideas for control here-
http://tncweeds.ucdavis.edu/esadocs/documnts/polycus.rtf

Thank you - this gives me hope
I will check out Rodeo - see if I can get it over here.
I am thinking that if you try to smother it (with a thick liner etc) it will just go sideways and find its way out!

In England you have to pay to get it removed proffesionally (have heard around £10,000) - but I presume its because it can undermine your foundations....the barn doesn't have foundations - but if we altered / built onto the barn it would be a disaster!

I still can't believe that its not on Ireland "noxious weed" list!
Sue

The active ingredient in Rodeo is Glyphosate which is the same active ingredient in RoundUp. The surfactant is different though. I'm getting a little voice on something with your comment that it can't be smothered because it would just go sideways and find its way out... can you please post a photo of the plant you are referring to as Japanese Knotweed?

Will do as soon as I get home from work
It's tiny at the moment...just poking its nose up
But I remember last year - it grew soooo fast!

Ok - here is a photo of the "knotweed" just beginning to show in the last couple of days.

It looks so pretty ...as the sun glints across the field...picking up the red tones...contrasting nicely with the golden yellow of the daffodils....just wait a couple of week and it will be a jungle out there!

I'm pretty sure that it is knotweed. No other pant can grow this fast - especially in Ireland
I've heard of a company in the UK that remove it, I could call them to ask their advice.

Such a pity - the land has lovely soil!
Sue

Yup, sure does look like knotweed.

Dear Sue, I gardened for many years in an area that had a large "grove" of Japanese Knotweed. I didn't know what it was (no Dave's Garden in those days) but it surely was a fascinating plant to watch. In early spring, (zone 5) I would break off all of the dried stems from the previous year. Then I'd get to watch the amazing growth rate. The blossoms attracted so many bees that you could hear them buzzing many hundred feet away, I tried pulling it up (in Spring) using the dead stalks as handles. It seemed shallow rooted and came up easily, but there was so much of it that I never made much of a dent. It is a real survivor. On the other hand - I'm a "land" person and the chance to add some is not to be discarded easily. I'd go with Equilibrium's advice.
Louise

Last week my good freind said she had a big bamboo like shrub that I could have. I went to her house and thought it was rather pretty and brought it home. After Googling shrub with bamboo-like form I discovered it was Japanese Knotweed. DH burned the entire plant in a huge bonfire we had to dispose of several trees we cut down last year.
Pretty good luck to have discovered the true nature of this plant before it established itself on my land. My friend said she bought this plant at a nursery orginally...geez. One comment I read online was Japanese Knotwood is Kudzu's evil cousin. I would hate to have been responsible for adding JK to the Kudzu problem down here in Tennessee.lol


Loretta

Gosh, with friends bearing gifts of knotweed... who needs any enemies! You seriously have to laugh when people sincerely try to share plants like that. They don't mean any harm but it's still funny. At least to me it is.

I called her right up and told her to get to digging out any of the plant left behind. I'm starting to get suspicious considering the horsetail reed and flag iris she sent to me last summer through DH. lol I'm very aware of the problems something like flag iris or horsetail could cause since my land drains into the river bottom of a fairly pristine river and swamp. All it would take is a small clump to get washed down in a hard rain and it would be all she wrote.

Loretta

Wow....but unfortunatley I can believe that you were given it as a gift...

Gunnera Manicata has taken over one part of Ireland (Its huge, wind battered and ugly - not as you see it in magazines!) The garden centres here continue to sell it !!!

Flag Iris is in lakes, ponds, gardens, by the roadside...anywhere with standing water.
(I have also been sent seeds of it in trades!)

The horsetail you refer to - is that what we would call reid grass? - I think its botanical name is Juncus effusis.
We had it head height thru our field, but managed to more or less irradicate it by cutting and turning the soil. A fairly large job, but at least this one is manageable

Sue

This is definately the Horsetail Reed, Equisetum hyemale
A native, herbacious conifer, aggressive from rhizomes, to 5 feet tall, stems jointed, heavily silicated. Cones formed on older stems. Well-drained soils near but not in water, tolerates occasional flooding, sun to partial shade. Hardy to Zone 5.

I have seen this stuff trying to take over a friend's backyard and it was accidently introduced.. Reeds began to pop up 25-30' from the original site it started.

The yellow flag iris is gone, I don't even like its look. After trying it in the pond potted up, then struggling to lift an overgrown 50# mass of roots out of the water after one year. decided to eliminate it.

Yes Gunnera does look quite ugly after the leaves get wind damaged or old. I can't imagine it taking over, people here beg for it in trades.

Loretta

Horsetail Reed

Ahhh...that's horsetail then!...I 'll watch out for that one!

I suppose that Gunnera is like any plant, perfectly well behaved in a normal situation, it's just that it loves water - so gets out of control in damp situations!

Please see my posting in Community Gardening about this wretched plant problem.
http://davesgarden.com/forums/t/733896/

Hi andy
Read your posting...poor you...talk about a poisoned chalice - sounds like a lot of work there!
I still haven't heard if anyone has ever got rid of it totally.

We haven't yet bought the land, but have been slowly removing and burning it at the area that is nearest to our land.

Here in Ireland it isn't thought of as a problem!...scary - one day we will wake up!
Will let you know how things proceed.
Sue

Willow - if you are already working the land infested with Knotweed, definately take it on. No sense letting someone else acquire it, and then have them ignore the problem. It is manageable, but I am not sure it is ever completely eradicated - we've just had it appear last year on our land, and we are fire fighting - I have had some success by using Graze-on sprayed over the area. this works well if it is in a field - only removes broadleaf, but won't effect grass - safe around animals - but do suit-up before you use it - and only on still days! Definately NOT organic, so use as sparingly as possible. For smaller infestations I am using it as a spot treatment: I cut the bottom out of an old bucket to use as a shield, then place the bucket over the plant and spray into the bucket. Leave the bucket in place to let the spray settle. Not a perfect approach (even using this precaution, I still managed to kill off a lovely Rose nearby).

Marestail I haven't found a solution for yet.

Good luck.