Anybody else here struggling with Japanese Knotweed?

my3cents

Markcheese wrote: »

The neighbours stuff is already a good six foot high, (just out of my reach) ,the stuff that I could reach and spray is only a foot or so... and the bits that are speading to my side of the fence a couple of inches... is it too early to spray it....
I started noticing it everywhere on the road side...

It just depends what works for you, where the stuff is coming up and what you have done to it before. I've got most of mine down to tiny little bits (no more than a couple of leaves) so I'm painting them with a home made glyphosate gel every time I see them. Before that I sprayed the slightly larger clumps (still quite small) with glyphosate at least every month from when I first saw them each year until they died down in autumn. And before that I had sprayed the mature plants that were over 2 meters tall twice a year once when they were fully grown in June and once at the end of August beginning of September.

Only problem is thats being going on for 15 years. You wouldn't notice the japanese knotweed anymore and to a casual observer it looks like I've beaten it but I'm taking no chances.

Markcheese

15 years ?? Eeek

I know someone with about 4 acres of it ... whats it like grazed by goats or even a lawn..

Spirogyra

Im still struggling with it. Am worried about the cost of treating it to be honest, worried that it could amount to several thousand, which frankly few of us have to spare....

my3cents

Spirogyra wrote: »

Im still struggling with it. Am worried about the cost of treating it to be honest, worried that it could amount to several thousand, which frankly few of us have to spare....

5l of glyposate is €40 and you'd need a lot of japanese knotweed to use 5l in a year.

iirc 5l will treat a over hectare at one of the higher rates, so even if you had a hectare of JW you'd start to fight back for around €80 a year with two sprays.

Spirogyra

my3cents wrote: »

5l of glyposate is €40 and you'd need a lot of japanese knotweed to use 5l in a year.

iirc 5l will treat a over hectare at one of the higher rates, so even if you had a hectare of JW you'd start to fight back for around €80 a year with two sprays.

Do I need to wear protective clothing or a facemask ? When is the best time of year ? Thanks

happyoutscan

http://www.boards.ie/vbulletin/showpost.php?p=95713649&postcount=9[/URL]

Already answered earlier in thread. Best of luck with it.

Kazbah

my3cents wrote: »

You'll probably find the genuine geotextiles thick enough to do the job a bit expensive but you can use more than one layer of cheaper material.

Do you think these geotextiles are common enough that most hard landscapers would have experience with them?

my3cents

Kazbah wrote: »

Do you think these geotextiles are common enough that most hard landscapers would have experience with them?

In Ireland I doubt there are many that have expereinice of the specific geotextiles used against JKW but there are plenty of UK firms that seem to be advertising they use them. Geotextiles have plenty of specifc uses, sealing up waste dumps so they don't leak, reducing the amount of hard core you need when making up a road etc., here you need one that won't burst or allow roots through. I think you could make a good stab at something similar with a couple of layers of builders plastic sandwiched between some of the heavier mulch geotextiles.

A neighbor has builders plastic and about 4 inches of gravel over an area I know had JKW on it and it never came through been down about 8 years but the JKW in that case wasn't a heavy infestation.

Markcheese

Yes yes yes, on protective clothing and mask .can you just buy a litre of round up now, I dont think you can now...
Theres a thing called a weed wiper, instead of spraying you wipe weed killer
onto plant,saves a lot of weed killer and only goes where you want it..

Kazbah

my3cents wrote: »

I think you could make a good stab at something similar with a couple of layers of builders plastic sandwiched between some of the heavier mulch geotextiles.

WOuld it not be a problem for drainage? I thought that was the idea behind the geotextiles that they are water permeable...

my3cents

Kazbah wrote: »

WOuld it not be a problem for drainage? I thought that was the idea behind the geotextiles that they are water permeable...

As I said there are different ones, I think the ones for JKW are impermeable, a bonded mix of materials for strength.

I think you need to put down a layer for drainage over the geotextile separator because there is no drainage through it. If you are flagging over the top you are creating a water proof barrier anyway.

Kazbah

Thanks totally not my area so a bit nervous of being taken for a ride and ending up with ruined paving in time!

my3cents

Markcheese wrote: »

Yes yes yes, on protective clothing and mask .can you just buy a litre of round up now, I dont think you can now...
Theres a thing called a weed wiper, instead of spraying you wipe weed killer
onto plant,saves a lot of weed killer and only goes where you want it..

Despite the new regulations I can still buy Roudup and Gallop by the 5l can in several places with no questions asked. 1l would be technically the largest size that should be sold to the amateur gardening market.

I've not seen a weed wiper recommended for japanese knotweed, I don't think they deliver enough of the required chemicals to be effective in this case.

my3cents

Kazbah wrote: »

Thanks totally not my area so a bit nervous of being taken for a ride and ending up with ruined paving in time!

Do half the job and see how it goes. Level up as best you can don't remove any roots then cover with whatever you can afford to use as a geotextile separator then cover in at least 4 inches of graded fill (803?) then top off with an ornamental gravel.

Leave that for 12 months and see what happens if its all OK after that put your flags down.

Edit> I would worry that whatever you do a contractor will end up spreading japanese knotweed around.

ithread

Hi all fellow Knotweed sufferers...here is a photo of some of my knotweed. Some seem to grow rapidly and some just seem to be growing at a snails pace? We have been treating it for nearly three years with Glyphosphate. It used to grow nearly 12 foot tall! Is this a sign it is dying back or shoud I still worry?

my3cents

ithread wrote: »

Hi all fellow Knotweed sufferers...here is a photo of some of my knotweed. Some seem to grow rapidly and some just seem to be growing at a snails pace? We have been treating it for nearly three years with Glyphosphate. It used to grow nearly 12 foot tall! Is this a sign it is dying back or shoud I still worry?

Looks like you are winning to me, but I suspect you'll be treating it for a few years yet.

Keep hitting all of it but if you don't get those really small rosettes of buds in your first two pictures then they will recover and eventually come back again - hit them while they are down and keep them down!

ithread

Hi mythreecents!

Do you mean I should spray those little rosettes..even now? They are only millimetres in size!

Thanks,

my3cents

ithread wrote: »

Hi mythreecents!

Do you mean I should spray those little rosettes..even now? They are only millimetres in size!

Thanks,

I always think the most sensitive part of a plant that will take up the most chemical quickly is the growing tip and those little rosettes are a mass of tiny buds. I only get individual stems coming up now but when I got those rosettes I painted them with a gel made of a 10% glyphosate and wallpaper paste. tbh I have no idea if it works except I found I didn't get and full stems coming from those rosettes. The rosettes are a type of fasciation cased by the roundup and I always think a bit more might be that killer dose.

jezko

It took ten years but after Digging, Burning and Spraying (With Commercial Herbicides ) I have a "clean garden" . I have seen this Plant being sold at flea Markets. I wish I knew it's an Offence to do so...

my3cents

jezko wrote: »

It took ten years but after Digging, Burning and Spraying (With Commercial Herbicides ) I have a "clean garden" . I have seen this Plant being sold at flea Markets. I wish I knew it's an Offence to do so...

It is an offence http://invasivespeciesireland.com/background/legislation/ireland/section-50/ and the list of plants and the full act is at http://www.irishstatutebook.ie/eli/2011/si/477/made/en/print

Section 50 of the act states:

(1) Save in accordance with a licence granted under paragraph (7), and subject to Regulation 74, a person shall be guilty of an offence if he or she has in his or her possession for sale, or for the purposes of breeding, reproduction or propagation, or offers or exposes for sale, transportation, distribution, introduction or release—
(a) an animal or plant listed in Part 1 or Part 2 of the Third Schedule,
(b) anything from which an animal or plant referred to in subparagraph
(a) can be reproduced or propagated, or
(c) a vector material listed in Part 3 of the Third Schedule,
in any place in the State specified in the third column of the Third Schedule in relation to such an animal, plant or vector material.

THIRD SCHEDULE

Non-native species subject to restrictions under Regulations 49 and 50

Part 1: PLANTS

.....

Japanese knotweed Fallopia japonica Throughout the State

ithread

Thanks!

I will maybe have a go at the rosettes (only have one small bunch) and then leave the bigger ones until I can get a good spray on the leaves! They are definitely poorer than last year and don't look that lush and green! Hopefully we are winning the war!

When they have died off we plan to lift some of the slabs in the garden and dispose of the old crowns if they are dead.

my3cents

ithread wrote: »

Thanks!

I will maybe have a go at the rosettes (only have one small bunch) and then leave the bigger ones until I can get a good spray on the leaves! They are definitely poorer than last year and don't look that lush and green! Hopefully we are winning the war!

When they have died off we plan to lift some of the slabs in the garden and dispose of the old crowns if they are dead.

tbh I wouldn't try and dig the old crowns out, words like Zombie spring to mind and you'll find the crowns are much more extensive than you can imagine. 7m across and 2m depth are commonly used figures.

If you keep the roots intact then spaying shoots that come up as they do after the main plant has been (partially) subdued can only help the whole plant take up the herbicide. As soon as you start breaking up the roots you start fighting a whole crop of new smaller battles.

ithread

When will I ever be able to get rid of those crowns...we have one that is huge!?

my3cents

ithread wrote: »

When will I ever be able to get rid of those crowns...we have one that is huge!?

If they are lifting the slabs or taking up the whole of a planting space then of course you are going to have to do something but there is the potential for secondaries to spring up wherever you cut into the roots and leave some behind.

You also need to be careful as technically you will then have a waste product that is classed the same way as asbestos when it comes to disposing of it - assuming you want to move it off site. Ideally burn any roots but how you do that in Ireland I don't know.

Markcheese

Put the crown in an old wheelbarrow, metal , metal tray or where ever it wont be on the soil ,ground ect.
Let it dry out... then burn it ...
Somebody told me pigs will dig up and eat the crowns.. but they will break up and spread the roots.. no problem if your putting lawn down , drama for anything else..

ithread

just an update....our japanese knotweed is very much present but it just doesn't look great. Some have lost leaves and others looked diseased.

We haven't touched the small rosette (haven't touched any of it) which now has lots of leaves...is this an attempt by the plant to consume as much energy as it can?

my3cents

The basic equation is if a plant has leaves it can feed the roots for another day.

The better looking stems need spraying. They are probably the result of the crown of the plant being killed or damaged so any healthy bits of root that are left will form bugs and try and grow.

I'd also treat the faciated buds and deformed growth as a means of getting glyphosate into the plant. In time all those bits that are showing spray damage now will recover.

ithread

We haven't sprayed yet this year at all. Are you suggesting we should spray/paste now if we get some dry weather?

It is just hard to know what to do with them!

beertons

Heard something on the radio a few days ago, that some fine dining restaurants are using Japanese knotweed in their dishes. Has a similar taste to rhubarb. Yee could be sitting on a gold mine!

my3cents

ithread wrote: »

We haven't sprayed yet this year at all. Are you suggesting we should spray/paste now if we get some dry weather?

It is just hard to know what to do with them!

If the leaves are sunning themselves then the plant is growing, if they have glyposate on them then they aren't.

Only time I would hold off spraying is towards the end of the year because a late spray before the plant looses its leaves is the most effective.

Standard recommendation is one spray to reduce vigor and stop the plants growing to big early in the year (before they get too high) and then a late spray in September before the leaves go.

Once you are getting the upper hand its just open season and spray whenever you can, in your case I'd be spraying whats remaining probably 4 times a year. Just think of any part of the plant you see above ground as a way of getting glyposate into it.