Japanese knotweed and Roundup stump killer.

[Wacky Racer]

Ok,

Have a problem with some of this stuff in the far corner of my (large) back garden, it is not a big area and comprises of 25 stems at most. I have done some research on the net and Youtube, and Roundup maximum strength stump killer seems the way to go.

I have treated the leaves with TWICE the recommended strength, and intend to keep doing it every couple of days for a week or so, to make sure it has the desired affect.

Apparently you see results in about three weeks, so I bought three packets to be on the safe side.

Two questions:-

The stems are now about a metre high, am I better just cutting the stem about a foot up and just pouring the stuff down the hollow stems, rather than on the leaves?

Also, any recommendations for buying a small bulk supply of the main ingredient glyphosate?

[Wacky Racer]

Equus said:

Mandat said:

I don't know about the actual treatment side, but what are you going to do with the rest of the cut stems?

This.

And if you're cutting them, be careful that you don't inadvertently spread or carry fragments elsewhere in the garden: the conventional wisdom is that you only need a fragment a couple of millimetres long for a plant to regenerate from.

I haven't actually cut them yet, and don't think I will following the above advice, but will ring my local council for advice when/if I do.

[Wacky Racer]

tokyo_mb said:

ou don't want to keep applying the glyphosate (or applying it at too high a rate), as doing so will just burn the leaves and they will drop off. Glyphosate works by being transferred down to the roots and killing the plant from there. That's why it takes a couple of weeks to see any effect. If you have destroyed the leaves the plant will no longer be transferring the food/energy it has created by photosynthesis down to the roots (technically a rhizome in the case of knotweed) and therefore you will not actually be doing any harm to the part of the plant you want to kill.

OK, thanks for that. Correct dosage in future.

[Wacky Racer]

Rangeroverover said:

DO NOT let any authority of any sort know you have knotweed, your property and those within 50m will be unmortgageable

OK, noted, but my property stands alone with no houses nearby and this stuff is in the corner of the garden 300 mtrs from the house.

I want to nip it in the bud so to speak. I understand it might be a three or four year job to eradicate it reading the net.

[Wacky Racer]

dave_s13 said:

Would it be worth getting a mini-digger in and excavating the stuff up and out in one fell swoop??

If it's only a small patch then a skips worth might get rid of it all.

Not really, as I said it's only about twenty stems not very tall, but anyhow access would be a problem.

Thanks anyway Dave.

So, the main thing I have learnt is don't overdo the concentration, and make sure it doesn't spread.

Thanks for all the helpful replies.

Appreciated.

[Wacky Racer]

Some very good advice, so thanks all...I'm taking it all onboard.

As I said, it's not a big problem...yet.

[Wacky Racer]

OK, Update.....

All the leaves have now dropped off, and the stems show definite signs of wilting....

Am I better injecting more Roundup DOWN the hollow stems NOW, or waiting until the autumn?