Knotty problem

[Padfield]

The track leading into my local woods is being invaded by Japanese knotweed (la renouée de Japon, as we call it). I've spoken to a local farmer (who grazes his sheep on the verges and probably owns at least part of the land in the woods) about the plant but he doesn't seem to have heard of it. He recognised he had a strange new plant but didn't know its origins or dangers.

I propose to write to the Administration Communale and ask them to intervene. Does anyone on these forums have experience of this plant? I'd appreciate advice on what to say. Currently it is restricted to one open, sunny area along the track. Is it likely to invade the deeper woodland? Will it compete with the sallows where my local emperors breed? Are there any reliable links you know containing information on how to eliminate it? I feel very uncomfortable watching it creep along the track towards my prime butterfly habitat.

Any advice would be appreciated.

Guy

PS - On a positive note, two Dukes were competing this afternoon for the prime spots on one stand of knotweed, by the river:





They obviously think this is a great plant.

[Gruditch]

Hi Guy, I was advised buy the local authority to use a, hmm can't remember based weedkiller. I started using Weedol, which they said was suitable, about 3 years ago. It has contained it, but not eradicate it, but I would expect it time that it would. Farmers Roundup is also very effective on anything, if you can get it. The trouble with both these product's is they have to be sprayed, or mixed in a watering-can and pored. That will kill everything else under, or around the knotweed. So I would advise to paint it direct onto the leafs. I expect you know this, but do not try to dig it up, or brake it off, BIG trouble if you do that.

Regards Gruditch

[Padfield]

Thanks, Gruditch. The AC would doubtless spray if they did it themselves - and I guess the farmer would too. Are these products safe enough for me to get a band of school students to paint the leaves? Our students can't graduate unless they clock up enough 'service hours', and conservation work is counted as service hours.

Guy

[Gruditch]

Yeah, perfectly safe.

You may find the groundsman at your school has some Farmers Round up, or the Swiss equivalent.

Regards Gruditch

[Matsukaze]

Glyphosate can be targeted at individual leaves by firing the spray down (or, more accurately, up) an empty soft drink bottle with the bottom sawn off.

[Piers]

Glyphosate can be targeted at individual leaves by firing the spray down (or, more accurately, up) an empty soft drink bottle with the bottom sawn off.

A very effective (if time consuming) method is to inject every individual stem with glyphosate using a large hypo. Perform this at six monthly intervals. This is the preferred method where the weed grows in sensitive areas.

Felix.

[Gruditch]

Yes glyphosate based that was it.

Regards Gruditch

[Lee Hurrell]

Hi Guy,

That's a shame. I saw some in France too

Dave asked about it last year - here's the link to that thread.

viewtopic.php?f=4&t=3617

At the bottom I mention a eradication firm I noticed when they had a van parked in my college car park, I imagine they use the same methods as mentioned above.

The patch I had it in has been planted with wildflowers which have gone crazy while we were away and have drowned everything else in that border (including the knotweed)

Cheers

Lee

[Padfield]

Thanks, Lee. I have informed the Commune and also a biologist friend of mine who was responsible for the Commune's action plan for woodland brown (Lopinga achine), which flies in those woods. This is a nationally scarce species - one of only a few lucky species that have their own action plans - so with any luck someone will do something!

Guy

[Padfield]

I sent an e-mail to the Administration Communale this morning and received a very reassuring answer from the Service des Forêts this afternoon - things happen quickly in Switzerland. They will treat the knotweed in two stages. First, in July, they will prevent the plants flowering, and then in September, when the sap is sinking, they will apply the final treatment, which will be taken down into the plant and, we hope, eliminate it. They knew about my patch of knotweed but not that the area was so important for rare butterflies and assured me it would be treated as a priority.

I very much doubt they will paint the leaves individually, but since Felix mentioned that I had a look at what would be involved and the task would be truly horrific.

Guy

[Dave McCormick]

Well the problem I had last year with the Japanese Knotweed, I managed to hack away all the known ones and they haven't came back this year, the roots of them are still there, but only one grew back which I found strange that more didn't. I managed to deroot a few and remove them. Also noticed its stronghold in a forest not far from my house, its not going to well there either, grass grew up and only a few plants grew, but only a few feet, they are no where near as bad as they were before there...could the cold winter have had any impact?

Guy, hope what they can do actually will stop the problem, seems this is an all to common pest of many areas and we have to do what we can to stop it before it spreads too much.

[JohnR]

I had Japanese knotweed in my garden and got rid of it by cutting it down and then spraying the regrowth at 6-12 inches with glyphosate, as mentioned. I think that I had to repeat this about four times over two years. If you can get it use the commercial/farmers version of Roundup and not the Roundup GC version which is the one you'll find in garden centres. Glyphosate becomes inactive on contact with soil.

[Neil Jones]

Glyphosate becomes inactive on contact with soil.

It works on Japanese Knotweed to an extent.

However that claim about becoming inactive on contact with soil has always
irritated me. That sort of rapid reaction that is implied by the statement which comes from Monsanto's claim sounds more typical of an explosive than a weed killer.

The truth is more complicated. N-phosphonomethylglycine or Glyphosate
inhibits an enzyme called 5-Enolpyruvyl shikimate 3-phosphate synthase
It is involved in the synthesis of aromatic amino acids. It kills the plant by stopping
it making protein. Animals don't have this enzyme but there are plenty of soil bacteria etc that do. The malaria parasite has it for another example.

Glyphosate can be come adsorbed on clay particles but it can also come off again.
and if your soil is peat or sand this won't happen. I seem to remember around 10% might be present after 6 months.

Monsanto were involved in a court case about this in France a while ago and as a result no longer make this claim.

Monsanto guilty in 'false ad' row
Man in field of sugar beets in Colorado, US
Monsanto's weed-killer, Roundup, is the world's best-selling herbicide

France's highest court has ruled that US agrochemical giant Monsanto had not told the truth about the safety of its best-selling weed-killer, Roundup.

The court confirmed an earlier judgment that Monsanto had falsely advertised its herbicide as "biodegradable" and claimed it "left the soil clean".

for more of the story see this from the BBC.

http://news.bbc.co.uk/1/hi/8308903.stm

[NickMorgan]

I am sure your AC will be able to deal with the Japanese Knot Weed and soon have it under control. It could take three years before it is completely gone, though. We find the best method of eradiction is to cut down the plants in September and then squirt herbicide down the remaining hollow stems. The following year any re-growth should be sprayed while it is fairly fresh. The process may have to be repeated over the next couple of years as some hidden bits of root persist.

[Padfield]

Thanks for these latest comments.

I will leave it to the authorities for now and keep an eye on what happens. I've made a careful note of your various suggestions and advice and if the problem persists after a few years may do something about it myself. I hope that is not necessary. The e-mail I received from the Commune was very comprehensive and reassuring.

Guy

[Zonda]

Himalayan Balsam is also a pest. I know some riverbanks close to me on the Frome, where the problem is probably too great for the injection method. Many hundreds of yards of riverbank, and up to 25yds from the rivers are affected. Forests of the stuff abound in several places, and it is a worry.

[JohnR]

Himalayan Balsam is also a pest. I know some riverbanks close to me on the Frome, where the problem is probably too great for the injection method. Many hundreds of yards of riverbank, and up to 25yds from the rivers are affected. Forests of the stuff abound in several places, and it is a worry.

This balsam is easier to control because it is an annual. Cut it before it sets its seed for several years and you will see a good reduction in plant numbers. Do not walk through it or touch it when the seeds have set because the pods explode firing seeds out for several yards in every direction.

[David M]

Himalayan Balsam is also a pest. I know some riverbanks close to me on the Frome, where the problem is probably too great for the injection method. Many hundreds of yards of riverbank, and up to 25yds from the rivers are affected. Forests of the stuff abound in several places, and it is a worry.

Agree 100%. This invasive sprawler has practically choked most of the native plants on the wetlands near me.