Japanese Knotweed - how to kill?

Mousewar wrote: »

Does anyone have a link to a good authorative source on treating Japanese knotweed? In particular, one that explains:
A) That spraying in August/September is the best course of action.
Why August/September are the months to do it.
C) The perils of any attempt to dig it out.

Basically, the landlord of the house opposite me returned yesterday and sprayed Roundup. (I know it's August but is it a tad early?) He seemed annoyed about waiting until August like I told him last month and said he thinks we should spray it all year round. He also said he plans to dig it out. He seems unwilling to accept my explanation for a, b, and c above so I'd like to send him a source he can't argue with.

Will he argue with Monsanto's own guide for JK eradication?

THE CONTROL OF JAPANESE KNOTWEED WITH ROUNDUP PRO BIACTIVE

Mousewar wrote: »

Thanks.
I think he'd argue with anything. I've explained why Aug/Sept is the best time to spray twice now. First time, in July, he said I was wrong and they only say that because Aug/Sept are "dry months" and it's best to spray when it's dry and since it was the middle of a drought (in July) that was a great time to attack it. Second time (yesterday) he said they just say Aug/Sept because they are the months of highest growth.
Anyway, I think he's just using regular roundup. Is that less useful or totally useless?

I cant tell you whats the difference between them. Im sure someone else will.

The crucial thing is that UNDER NO CIRCUMSTANCES should he attempt to dig it out because much of the plants will still be alive, even if the Roundup appears to kill the visible stems and foliage.

I know absolutely nothing about this plant but see it popping up locally on ditches and the signs have gone up beside them.
My mother is of an age where she says (she thinks) she remembers them in her childhood (although she calls it bindweed) and that there was never a panic over it, it was just left grow and nothing disastrous happened??

TomOnBoard wrote: »

They're two different plants, although their leaves do look somewhat similar. being heart-shaped. JK is waaaaay stronger than BW. JK smothers an area and is self-supporting while BW grows by clinging to another plant or structure and climbing up.

They're both invasive and each requires multiple doses of Glyphosate to kill them, but while BW might be a 3 on a scale of 1 to 10 in terms of damage it can do to other plants, JK is a 10. BW is a 0 in terms of potential structural damage it can do, while JK is a 9 or 10.

Put another way, BW is George W Bush and JK is Trump...

Mam made the comparison to ivy that takes over and smothers other plants/trees and yet there's no panic about it.
I'm obviously not getting the whole JK debacle.

Mousewar wrote: »

Thanks.
I think he'd argue with anything. I've explained why Aug/Sept is the best time to spray twice now. First time, in July, he said I was wrong and they only say that because Aug/Sept are "dry months" and it's best to spray when it's dry and since it was the middle of a drought (in July) that was a great time to attack it. Second time (yesterday) he said they just say Aug/Sept because they are the months of highest growth.
Anyway, I think he's just using regular roundup. Is that less useful or totally useless?

best time to spray most weeds is when they are in maximum foliage just b/4 they flower thus to prevent the spread of seeds and further re infestation

maximum foliage means more chemical is taken and travels further into the root system

HOWEVER JK does not spread through fallen seeds , instead it spread through bits of roots carried in clay etc
It can lie dormant in same and suddenly burst into growth decades later, I have first hand experience of this

cutting or topping will spread it more , cos the roots will travel further underground and I've seen it actually burst up a tarmac drive way, again it may take decades

I've meant to post some pics here of sites we've treated but haven't got to visit them yet due to the drought we are otherwise occupied

regular roundup or garlon will work initially but will not give full long term control

good idea to add a sticky or wetting agent (presto or wetcit etc,) to ensure better adhesion to the leaves especially after the long dry spell

my3cents wrote: »

I've just got my hands on some Grazon and I'm torn between using it now or waiting for another few weeks and hammering it with Roundup.

Its tricky site (not even mine but its near enough to be worth my while keeping it under control) by a river with steep banks .

Wouldn't a decent size drone be able to handle a miniature sprayer (2 litres or so) with a small ni-cad battery, pump and nozzle or two?
The down draft would help as well, I expect, and a dash of food colouring in the Roundup would help avoid missing bits.

If you spray the stuff now and it's dead come end of september, what do you do with it then? Take it up and dispose or leave it there? Will it eventually wither to nothing?