Jap.knotweed

[Trailoftears]

Something I meet more and more,and also due to media scare stories makes most of my customers faint at the very sight of!As much research suggests glyphosate works surprisingly well.I encounter it regularly alongside riverside properties,which figures given its propensity and talent to use railways,canal and rivers as easy highways.I find it surprisingly easy to control at the standard rate of 50:1 re: glyphosate application.Given its glossy/moisture repelling leaf structure,I find it effective to either trample it,or give it a damn good thrashing in a Fawlty Towers style pre application!You could also use a leaf surfactant too I guess-You cant beat thrashing an alien species with a big stick tho-I'm thinking our caring Tory gov here...As to Jap.knotweed and Glyphosate-,it controls it- note the lack of the magic word 'eradicate',apparently,the rhizome structure can if needed,sit tight for 20 odd years!Now thats a robust lifeform.

[Muddy42]

I have yet to find a plant or tree that can survive the standard treatment of cutback and then 1 to 3 applications of fresh max strength glyphosate. The last two treatments are probably only needed because I missed some the first time or I am impatient.

[topchippyles]

Dreadful stuff to try and get rid of it grows so deep and will grow between rock's and even though concrete.

[topchippyles]

Only way I have seen is to dig down deep and remove the hole area 

[Will C]

We have had success with Cutting it off (burned on site) with loppers at about 8 inch high. Then stick the pointy end of a saw file down through the centre of the stem and fill with max strength roundup in a handheld sprayer - had ink in as well to see where you have been. 
we went back in the spring and sprayed roundup again on the few regrowth bits. 
it was time consuming and a shit job but it has never grown back since and was probably 8 years ago.

 

I didn’t write the job spec just carried it out but it worked.

[Muddy42]

1 hour ago, Will C said:

We have had success with Cutting it off (burned on site) with loppers at about 8 inch high. Then stick the pointy end of a saw file down through the centre of the stem and fill with max strength roundup in a handheld sprayer - had ink in as well to see where you have been. 
we went back in the spring and sprayed roundup again on the few regrowth bits. 
it was time consuming and a shit job but it has never grown back since and was probably 8 years ago.

 

I didn’t write the job spec just carried it out but it worked.

Yes that works well, I've even heard of people using a big syringe.

[sandspider]

Is this best done towards Autumn, when the plant is drawing reserves (and therefore glyphosate) back into its roots? Or will it work at any time of year?

[Muddy42]

6 minutes ago, sandspider said:

Is this best done towards Autumn, when the plant is drawing reserves (and therefore glyphosate) back into its roots? Or will it work at any time of year?

 

I'd do it any time, the sooner the better.  You can also make the reverse argument, the shoots are renewed every year so in early spring plants have yet to build up reserves so you are hitting them when they are weakest. Plus its easier to poison smaller shoots than larger ones that you would have to cut back anyway.

[Grassyass]

If you leave it until the autumn it will have dropped all it seed heads and they will grow back again, In our experience it takes about 5 years to get rid of it , we do the stem injection as well as spraying  ,but the sooner you treat it the better , 

[Spruce Pirate]

Quite a while ago we used to spray it with glyphosate in Round-Up form.  It always seemed to shrug it off unless sprayed later in the year when it went into effervescence.  Never seemed to have much effect when sprayed earlier in the year so interested to hear different stories of how to treat.   Haven't done it in years, but do have a wee bit to treat now so I might try hitting it early.