Japanese knot weed

pipeband

If anyone can help with any ideas how to get rid of Japanese knot weed i would be very grateful. its like a forest in my daughters garden...

ducksmalone

pipeband wrote: »

If anyone can help with any ideas how to get rid of Japanese knot weed i would be very grateful. its like a forest in my daughters garden...

i have experience of how this should be removed..............properly! if its anywhere near your daughters house,this is not good news.

how big is it? please throw up pictures of it. but dont pick it up and throw it in the bin for starters.

LK_Dave

Can you send a picture of the garden and the base of a plant up close?

I thought Japanese knot weed lost its leaves and died back during the winter months.
If so, what I would do is cut the existing plants a couple of inches from the ground and spray the new shoots with something like Roundup or similar. You will have to ensure the roots are dead before you dig them up and dispose of them.....I would burn them.
That is how I would do it.
I wonder would this Japanese knot weed be a good plant to fill in the gaps in my miscantus/elephant grass?

ducksmalone

LK_Dave wrote: »

Can you send a picture of the garden and the base of a plant up close?

I thought Japanese knot weed lost its leaves and died back during the winter months.
If so, what I would do is cut the existing plants a couple of inches from the ground and spray the new shoots with something like Roundup or similar. You will have to ensure the roots are dead before you dig them up and dispose of them.....I would burn them.
That is how I would do it.
I wonder would this Japanese knot weed be a good plant to fill in the gaps in my miscantus/elephant grass?

moving knotweed is never a good idea unless you know what your doing.If it is dug up,then there is a strong chance that the soil around the knotweed is contaminated also.just removing the roots is not doing a thorough job.

anyone ever see the damage this does to roads,sewers,walls buildings etc?

it only takes 1 seed for this bugger to start growing again,and it grows quickly in the right conditions.

LK_Dave

ducksmalone wrote: »

moving knotweed is never a good idea unless you know what your doing.If it is dug up,then there is a strong chance that the soil around the knotweed is contaminated also.just removing the roots is not doing a thorough job.

yes, i agree.... what I’m saying is to trim the plants down when they are in a dormant state and kill the new shoots with a strong week killer....this will take a number of doses probably over a number of months

mp22

The BBC had a programme about this,if you let the stems grow till they are about 20mm dia,cut them off 18 inches from the ground and pour a handy drop of the strongest week killer you can get down the stem.seems to sort them out.

ducksmalone

mp22 wrote: »

The BBC had a programme about this,if you let the stems grow till they are about 20mm dia,cut them off 18 inches from the ground and pour a handy drop of the strongest week killer you can get down the stem.seems to sort them out.

any idea when this programme was on?
i'll have a search around later for it,i do know there are a few different types of knotweed. the knotweed i removed,with an environmental crowd in london, had places zoned off and did some serious digging to remove the Japanese knotweed. talk later

pipeband

My husband dug up the garden a few weeks ago against my wishes but now the only place it seems to be growing is against the wall where he did'nt dig, But im afraid it will come back worse because of the dig. we sprayed it with roundup a few months ago and i think it fed it !!!

dardevle

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some useful info on what you are battling here:

http://www.conservationvolunteers.ie/images/buttons/submenus/news_and_advice/downloads/naa_bpmg_jk.pdf

removal is not easy and if you can arm yourself with as much knowledge about the plant and how it grows and spreads you will save some pain,

i am currently in year 2 of a program to eradicate it from a local park - cut and sprayed the stems on 3 seperate occasions last year, which slowed down growth considerably but it has still returned to the parent sites this year, planning to spray again this year and realistically next year also,

ps;
any stems cut must be collected and stored until completely biodegraded(black plastic on a hardstand surface not soil)

goodluck!

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doctor evil

I have this in my garden, its a nightmare.

I don't have access to weed killer at the mo so I have been pulling it up by the base as close to the soil to get as much of the root as possible. Unfortunately it is growing by the walls in under the foundations. It is also in thick with the apple tree and other shrubs.

The roots and about two inches on the stem goes into the bin. The stalks and leaves I chop up and put into the compost, am I ok doing this? I am super careful to make sure there is no root present.

pipeband

Thank you all for your help will take all on board... think its going to be a long haul getting rid of it thanks again

dardevle

doctor evil wrote: »

I have this in my garden, its a nightmare.

I don't have access to weed killer at the mo so I have been pulling it up by the base as close to the soil to get as much of the root as possible. Unfortunately it is growing by the walls in under the foundations. It is also in thick with the apple tree and other shrubs.

The roots and about two inches on the stem goes into the bin. The stalks and leaves I chop up and put into the compost, am I ok doing this? I am super careful to make sure there is no root present.

try to resist the urge to pull it up since the roots are rhizomic in nature which simply put, means that each root that is seperated into pieces has the potential to re-grow as a new plant.

composting any part of the plant is ineffective and can result in more spreading:(


in my opinion you would be better to wait until you have access to weedkiller ....... it is still early in the season and prime spraying period will be around july - aug.


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ducksmalone

dardevle wrote: »

try to resist the urge to pull it up since the roots are rhizomic in nature which simply put, means that each root that is seperated into pieces has the potential to re-grow as a new plant.

composting any part of the plant is ineffective and can result in more spreading:(


in my opinion you would be better to wait until you have access to weedkiller ....... it is still early in the season and prime spraying period will be around july - aug.


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i agree with the 1st part of your advice,in resisting the urge to pull it up. but spraying it with weedkiller shur if that worked there would be no need to dig it up.


would still like the OP to put up pictures of it please.

dardevle

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as stated previously the plant stems are cut and then a high strength glyphosate based weedkiller is introduced directly into the remaining hollow stems where it is carried to the roots,

the reason multiple applications are required is because at any given time, a percentage of stems are at pre-emergence stage while the weedkiller is post emergent, so only works on visible growth.




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LK_Dave

dardevle wrote: »

weedkiller ....... it is still early in the season and prime spraying period will be around july - aug...

ducksmalone wrote: »

but spraying it with weedkiller shur if that worked there would be no need to dig it up.

This is the biggest mistake people make with weed killer – waiting too long in the growing season and then spraying.

In order for a week killer such as Roundup to work (or any weed killer for that fact) you must infect the weed when its growing at it’s most vigorous - you need leaves for a glyphosate weed killer to perform its function most efficiently/productivity. With a grass/rhizome crop this is usually in early May (of course this depends on the weather) before it heads to seed. When it heads to seed late June/July its really too late and you end up literally throwing money down the drain. Spraying a full grown crop in June/July when it has gone to seed will have little effect on the roots/rhizomes. Ditto for spraying too early.

Cut the crop/weed this time of the year(before it starts to grow), after the winter it will have turned brown and be to the most part leafless. With such a weed, cut at a height of about 6 inches above the ground. Remove the brush and burn or somehow quarantine to decompose. This will open the ground up to light and get the roots sprouting. The new sprouts will race skyward and produce fresh leaf. When the leaf is about quarter size of a full grown then is the time to spray.

When spraying Roundup, you need about 6 hours of dry weather. 2 before and 4 after. Spray on and under the leaf and on the ground. Roundup will take about 7 to 10 days to have a noticeable effect. Leave if for about two weeks and spray again. After another three weeks, the standing weeds should be browned and dead - cut and remove the brush again but this time try to cut as close to the ground as possible. Burn or somehow quarantine the brush.

Keep this regime up until you have eliminated/killed the weed. You will then probably have to dig up and remove the dead rhizones - again burn or quarantine to decompose.

After cutting it may also be a good idea to spray the ground with a pre-emergence weed killer...if you can get it.

dardevle

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With a grass/rhizome crop this is usually in early May (of course this depends on the weather) before it heads to seed. When it heads to seed late June/July its really too late and you end up literally throwing money down the drain. Spraying a full grown crop in June/July when it has gone to seed will have little effect on the roots/rhizomes. Ditto for spraying too early.

^^^^^
the vigorous growth period for knotweed is May thru July and it does not flower until August.....by spraying now you would only affect a small percentage of new shoots with much more to come later in the year - many applications are required throughout the growing season.

again have a look at the best practice guide:

http://www.conservationvolunteers.ie/images/buttons/submenus/news_and_advice/downloads/naa_bpmg_jk.pdf

also while eradication by excavation is probably the most successful, in reality it is beyond the scope of most homeowners.


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Thoushaltnot

I'm hoping to not have to use weedkiller, so I'm throwing everything I got at it to weaken it. I'll be digging out as much of the main root system as possible, drying it and burning it.

Then putting down a heavy layer of weedsheet/newspapers/carpet, leave it a few weeks, see what's trying to grow that I missed and get that out too and repeat that over the Summer to weaken it.

At some point, I'm planning on sieving the soil with a fine riddle, as the soil itself is excellent and I'd like to grow some food (but this year it'll be in containers.) As it's spread outside my patch and another nearby plot looks to have been "gifted" the same topsoil, it looks like I'll have to excavate and isolate my patch with barriers.

I've read that an application of lime did the job before.

I've also read that you keep it cut to weaken it (it'll grow from a little fingernail amount of rhizome or from stems, apparently, so DONT COMPOST) then at the end of the Summer, let it grow tall enough to start flowering, hit it with glyphosate and that worked for someone else.

The shoots are edible (cook like rhubarb) but as it's choc full of oxalic acid, you can only eat a small amount.

Aside: I don't know if it's the soil or the knotweed but I have huge earthworms. Anyone else notice that?

magicbastarder

Thoushaltnot wrote: »

I've also read that you keep it cut to weaken it (it'll grow from a little fingernail amount of rhizome or from stems, apparently, so DONT COMPOST)

does anyone know how long such plant matter would stay alive in a compost heap, with no sunlight to provide food for growth?

dardevle

magicbastarder wrote: »

does anyone know how long such plant matter would stay alive in a compost heap, with no sunlight to provide food for growth?

stems that have been removed will not regenerate once they have been thoroughly dried out and achieved the orange/brown colour that is seen during winter......stems that are left in contact with soil or water will re-root in a matter of a couple of weeks,

rhizome material on the other hand, can remain dormant for up to 20 years and a piece as small as 10mm can produce a new plant in as little as 10 days (uk trials).



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Thoushaltnot

I have read that elsewhere - that the rhizomes can still be viable and regrow up to 20 years later.

It's a bit of a monster alright.

POCKET.ROCKET.

I am lead to believe that Japenese Knot weed does not set seed. The female sex of the plant was only introduced and not both male and female. Thus the only way for this plant to reproduce is by its rhizomes.

So by very careful where you remove soil from sites that have the knot weed present.

dardevle

POCKET.ROCKET. wrote: »

I am lead to believe that Japenese Knot weed does not set seed. The female sex of the plant was only introduced and not both male and female. Thus the only way for this plant to reproduce is by its rhizomes.

So by very careful where you remove soil from sites that have the knot weed present.

this is true of the japanese knotweed, also over the last number of years a hybrid has appeared (bohemian knotweed) of which both male and female plants are now present and can spread from seed, it is a cross between japanese and giant knotweed and the appearance is very similar, thankfully it is still a rare occurrence in the irish countryside.




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Zuiderzee

In the UK they are introducing an aphid and a fungus that are specific predators for the knot weed - it is a horrible plague of a weed, hate the damn stuff

ducksmalone

POCKET.ROCKET. wrote: »

I am lead to believe that Japenese Knot weed does not set seed. The female sex of the plant was only introduced and not both male and female. Thus the only way for this plant to reproduce is by its rhizomes.

So by very careful where you remove soil from sites that have the knot weed present.

I'll just ad to this comment if thats ok Pocket.

im not sure if it is illegal in Eire to remove and transport Japaneese knotweed,as far as i know in the UK it is.

why might it be illegal you ask? well,as pointed out earlier in the thread,this stuff has the potential to undermine buildings roads and infrastructure,thats how serious environmentalists take this stuff.

If someone is planning on removing this weed from the surrounds of their home,it would be advisable to do it in sections,treating each area thats been worked on as a contaminated area,use tarpaulin or rolls of sheeting on the area thats been worked on,even treat the mud on your boots as contaminated,she shovel,the wheelbarrow.

We never saw pictures of this,so it mightnt be Japaneese knotweed at all

dardevle

Zuiderzee wrote: »

In the UK they are introducing an aphid and a fungus that are specific predators for the knot weed - it is a horrible plague of a weed, hate the damn stuff

a very dangerous road to go down (imo).....chasing after an introduced invasive species by introducing other non native species is a one way street - no going back once the damage is done.:o






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Zuiderzee

dardevle wrote: »

a very dangerous road to go down (imo).....chasing after an introduced invasive species by introducing other non native species is a one way street - no going back once the damage is done.:o......

I was aware of that - cane toad in Oz etc. but the Brits seem to have very carefully researched this one due to disasters in the past, and there have been some successful examples

Zuiderzee

Thoushaltnot wrote: »

I'm hoping to not have to use weedkiller, so I'm throwing everything I got at it to weaken it. I'll be digging out as much of the main root system as possible, drying it and burning it.

Try home made weed killer on the leaves, at least you know what it contains - just vinegar, salt and washingup liquid.

There is also an Irish made version with a higher concentration of aecetic acid - owk.ie

You can get cheap malt vinegar and sprayers in Aldi, I got a sprayer specifically for herbicide and home made insecticide, use another for liquid fertilizer (nettle and seaweed tea) and diethene or copper sulphate, about the only commercial chemicals I use in the garden