Japanese Knot Weed (Merged)

evilgoose

Wow lots of replies here, i've not had time to read through them all. Knot weed is a personnal bugbear of mine - I do feel that LA should be looking seriously at tackling this problem, as without it, it will continue to get worse and worse. But then I guess every LA would have to act, otherwise it's just going to respread.

I think it was countryfile along while ago that covered some info on the plant. The best time to use weedkiller is in the late summer/early autumn as the plant starts to die back. It draw the nutrients from the stems back into the rhizome, so cut them back to just above ground level and spray into the cut tube left by the cutting. It may require several years of treatment to kill the plant.

JKW has to be buried in special area's of landfill at depths of 6 meters! it's a lovely plant!

Wordsmith

Thanks for responses. I have about half an acre of knotweed and I estimate that there must be a couple of thousand stems, so injecting each individually would be pretty arduous methinks.

Does anyone know if goats will eat them? I know that this will not get rid of them, but if I can keep some at bay while tackling smaller patches this might be more achievable. (For anyone worried, getting goats is part of the home plan anyway - I wouldn't be getting them just for the knotweed.)

And I still have the problem of a stream running along one boundary - the stream continues for about 1.5 km and then flows into a lake (which is used for providing water to humans) - would any herbicide I use be diluted enough by then not to be a problem? There's no other chemicals used on the way, since the stream runs through forestry. There are no fish in the stream, although obviously there may be other wildlife that drink from it.

What about strimming it all down (and getting rid of the stems and leaves sensibly) and then covering the area with black plastic - do you think the JK would die off after maybe a couple of years?

Any further thoughts would be most welcome.

evilgoose

Wordsmith wrote: »

Thanks for responses. I have about half an acre of knotweed and I estimate that there must be a couple of thousand stems, so injecting each individually would be pretty arduous methinks..

From what I've seen (good ole countryfile) injecting seems to be the most effective way. National Trust have tackled vast areas of the stuff that way. - sorry!

Wordsmith wrote: »

And I still have the problem of a stream running along one boundary - the stream continues for about 1.5 km and then flows into a lake (which is used for providing water to humans) - would any herbicide I use be diluted enough by then not to be a problem? There's no other chemicals used on the way, since the stream runs through forestry. There are no fish in the stream, although obviously there may be other wildlife that drink from it.

If injecting rather than blanket spraying you shouldnt have any issue with water course problems (but seek more knowledgable advisor than me!)

Wordsmith wrote: »

What about strimming it all down (and getting rid of the stems and leaves sensibly) and then covering the area with black plastic - do you think the JK would die off after maybe a couple of years?
.

You'll have to cut it several times through the year and before it's seeds form. The plants rhizomes can be several meters down. I'm not sure if the black plastic will prove much of a barrier.

"Cutting the stems once will result in new shoot emergence. However, repeated cutting may eventually tax the plant of its resources. Cut each time the plant reaches six inches tall.

At a minimum cut at least 10 times per season (twice a month April through August) and monthly cuttings afterwards, for 2-3 years is necessary.
You may not want to attempt manual removal of knotweed unless you are willing to continue the process for the entire growing season and continue for several additional seasons. Research has shown that cutting once per month from April to October resulted in an increase in stems after 3 years." - this is mentioned on several American sites regarding JK control.

If the weed is on adjacent land (and up the stream up mention) then it will reoccur unless those areas of the JK can be dealt with also.

I'm not sure about the goats, but they will eat most things, what I would say is that the plant can spread from small fragments of the plant, so there is a chance the gost may help create new plants and worsen the problem.

Wordsmith

Thanks, evilgoose.

RAS

It is an absolute cow and has loved the very wet summers we had the last two years.

When we tackled it in the cemetery, we cut out the shoots when they were six inches high, again and again over the season and after two years it was very much reduced. but it still needs monitoring.

lexie55_2

Just read a Jeffrey Archer book (A Prisoner of Birth), knotweed is mentioned in a chapter - think he exagerrates a bit...

Mojisola

Wordsmith wrote: »

What about strimming it all down (and getting rid of the stems and leaves sensibly) and then covering the area with black plastic - do you think the JK would die off after maybe a couple of years?

I've heard of knotweed coming up through a concrete floor so I don't think black plastic would be very successful.

RAS

In Cornwall or Devon, they abandoned a petrol station. The tank appeared to be leaking, and then they discovered that JK had drilled its way into the concrete tank.

Have also seen pics of it growing inside a house, having grown through or under the footings and then come up where the floor met the wall.

lexie55_2

lexie55 wrote: »

Just read a Jeffrey Archer book (A Prisoner of Birth), knotweed is mentioned in a chapter - think he exagerrates a bit...

Maybe not..