Japenese Knotweed Spraying

About 10 days ago I sprayed a solitary Japanese Knotweed stalk that was about 10ft high.

Came back to it a week later and it had shed most of its leaves, which were carefully removed and burned, however, the stalk remains just as healthy as it was before being sprayed and there are new leaves and leaf buds forming all along the branches.

I sprayed it with Clinic Ace at 250ml per litre and intend to inject the stem with a neat solution of the weedkiller, hoping that will have a more pronounced effect.

Active Ingredients:360 g/l glyphosate (acid equivalent) present as 480 g/l (41.1% w/w) of the isopropylamine salt of glyphosate.

The customer has contacted the council but they have no interest in helping out. Also, (as much as I hate to talk badly about customers, she's a somewhat of miserly old so-and-so and must think that weedkiller is free or grows on trees). Despite my continual warnings that her house may be rendered unsellable, she is not interested in buying some serious weedkiller to eradicate it. I'm certainly not going to cough up money on her behalf, which will never likely be seen again.

Does anybody have recommendations about Clinic Ace that could be more effective, or a cheaper and more potent alternative? Maybe I used too much for the initial dose, so it shed its leaves in somewhat of a panic.

Many thanks

 

I have controlled Knotweed with Glyphosate before now. At 10ft the stem was much too old. Cut it down, and treat the younger growth as soon as it comes through. Educate your customer on the viscousness of the plant and how much it will cost to get it under control.

 

Many thanks for your advice. Maybe it is too late to kill it but it has definitely knocked it back somewhat and I'd been advised to spray it in the summer time when it reached full height. Will spray the new foliage next week and inject the stems with neat Clinic Ace. Maybe she'll have to cough up for some root and stump killer which is cheap and incredbly strong and as only one stem (amazingly) makes an appearance each year, only a small amount should be needed.

Am slightly apprehensive about cutting it down though as there's nowhere to disopse of it safely and I definitely won't be putting any of that evil stuff in my vehicle to take away. If she's got a garden incinerator or some kind of barell or something, I'll burn it but otherwise, it will have to stay intact as putting it in the garden waste bin that the council empties would be incredibly irresponisble on my part (and probably illegal) as they compost the waste and sell it.

 

If you can't burn it, see if you can put it somewhere to totally dry it out. That'll kill it

 

Many thanks @Zigs

The old dear's garden is somewhat of a shade spot and surrounded by huge sycamores, ashes and willows but there is one corner that gets sun most of the day so will put it in some form of hefty container that will dry it out but not allow the stalks to produce rhizomes which they are capable of doing in moist conditions.

Spoke to a local garden centre about their products and they have a Roundup stump killer that also kills Japweed and has quite detailed instructions that suggest spraying the top and undersides of leaves in summer when the plant is at full height and in flower, but not in autumn time. Repeated application may be necessary.

The concentration of the stuff I used kills Horestails (Equisetum arvense) which are incredibly resistant to weedkillers, so may use it one more time on the Jap demon and get the old lady to open her cobweb-filled purse (heaven-forbid!) for some stump killer if it fails. Or simply let her house crumble if she doesn't because she's my least favourite customer anyway and I'm swamped with requests for bigger, better paid and less hazardous jobs anyway.

 

Other thing I do with things like bindweed and couch grass roots is to ferment em out in a dustbin full of water, nothing survives that, and you get a liquid feed.

I love the smell of liquid feed in the morning

 

Mowerman, may I point out what you are doing. What I have done, is illegal anyway? However, someone needs to stand up to the problem of knotweed, AND Himalayan Balsam.

 

As far as I know the top growth is pretty much ok, its the roots that are invasive, unless of course you intend taking cuttings

 

There's no accounting for taste

 

You are right Pete, the root system is the problem but that needs to be tackled through the leaves.

 

Just regarding disposing of cut down plant material, its not likely to spread
.

 

The thing is Pete, you CANNOT remove any part of the plant offsite without a license, and they are as rare as hen`s teeth.

 

Just an update.

Visited the garden a few days ago and the knotweed looks like its been dragged through hell and back several times. The new foliage that appeared has died (apart from one new, green leaf near the top ) and the rest of the remaing stems and leaves are turning brown and curling up a treat.

I just need to obtain a syringe to inject some neat Clinic Ace into the main stem and watch it die back... at least for this year.... as next year it will, without a doubt, be back with a vengeace. It's like a rinse and repeat cycle to remove an oil stain from your best shirt.... although sligtly more persistent.

There's absolutely no signs of new leaf buds or flower buds forming, just a very sickly plant (bless its little cotton socks ).

 

Mowerman, keep checking weekly for new growth and spray accordingly.

 

Farmers shops are the best/easiest place to get them from:

Syringes http://www.countrywidefarmers.co.uk/pws/ProductDetails.ice?ProductID=15127

Needles http://www.countrywidefarmers.co.uk/pws/ProductDetails.ice?ProductID=15128

P.S. Alternatively, you could run the gauntlet of a High Street chemist, or find something used to get a replacement from your local syringe exchange.