Japanese knotweed

[bluesmoke2stroke]

Hi.
The biggest problem with knotweed is it always seems to be on someone else's land!!
It's a plant and not impossible to kill by any means.
We had some adjacent to our property on an old railway embankment,it was ports authority land.they got a proper 'knotweed' specialist on it who sprayed the 7ft forest(on a windy day btw damaging everything within 10ft of the bloody knotweed!).
About a month later the guys came back and chopped down the now dying braces to about 1ft clumps and burnt the branches onsite.
They then painted the weedkiller onto the stumps liberally and were done.
They were doing this with a glyphosate based weedkiller available to anyone made Bayer called 'super strength glyphosate'.
The flollowing spring one little stump tried to regrow but I gave it a spray with the stuff guy left me and it hasn't come back,it's been 5 yrs now and this is the first year other plants have grown in the area!..so it's potent stuff.
Spraying when they're flowering gives best results but as they're 6ft+ at that time it's not the easiest.so getting at them end of April when only small is easiest.
Just takes a bit of graft and persistence.

[Tango13]

I read somewhere that one way of killing off is to pump high pressure superheated steam into the ground to boil the roots alive

Not sure how effective it is but boiling the bd stuff alive would be satisfying if nothing else.

[Condi]

No need to panic, just get some glyphosate weedkiller off ebay (360g/l) and inject into the stem, or spray the green parts of the plant.

It will take a little while to die down but will kill a lot of the vegetation. Then chop, burn, and respray and further growth.

The root systems are so huge, and it grows from runners rather than one or 2 points, so killing the entire plant will take a little while, but roundup or similar will do the job.

[wilwak]

We had a bad attack of knotweed on the meadow adjoining our street.

I bought a 5L bottle of Rosate on EBay and with the full permission of the landowner sprayed all the greenery every few days.

The weed killer is drawn down in to the roots so pretty of green leaves is an advantage.

Keep an eye out for other small plants popping up even 10m away. When they do, allow them to grow a few green leaves before spraying them.

Once all are dead keep an eye on the area for the next couple of years.

We had a couple pop up the follow Year that I promptly despatched.

We have now been clear of it for 5 years.

We originally had about 10 plants in a 30m circle.

[TeaNoSugar]

Thanks for the advice - sounds like industrial strength glyphosphate is the way to go. Probably best done asap to get it while the thing is covered in leaves?

Something like this in a pump-spray bottle?

[Condi]

TeaNoSugar said:

Thanks for the advice - sounds like industrial strength glyphosphate is the way to go. Probably best done asap to get it while the thing is covered in leaves?

Something like this in a pump-spray bottle?

Rosate/Roundup/Gallup whatever, its out of copyright now so there are hundreds of generic brands. Roundup is probably the best out of all, dont ask why, they're all the same active ingredient, but they'll do the same job eventually.

Water down correctly if you're spraying the leaves, or inject neat into the stem. Dont spray neat roundup on the leaves, you'll burn them before the chemical has chance to move into the plants transport systems and move to the roots.

[Wacky Racer]

It needs to be Roundup TREE & ROOT killer.

Not ordinary Roundup.

This is important.

[Harry Flashman]

It's me who is considering buying a house with a clump of this stuff in the garden. Treatment started last summer by the seller with a company who repeat kill and give a 10 year guarantee - needed for any mortgage.

The plant is not visible just now: I noticed because there is a patch of garden with a big orange fence around it and obvious treatment going on inside.

Apparently I was the only viewer that day who asked what the zone was! To be fair to EA and seller, it is in the information pack I got later on.

All academic, though - we won't get the house as there is a developer bidding on it for cash, so our offer (we'd have to sell our house) is not being entertained.

[crankedup]

Environment angency have been. use trialling insect bugs which positively love to eat the sap from knotweed. Love it so much they eat nothing else! Although this little bug thrives on the knotweed thier dietary needs do not destroy the plant, but considerably weaken it. Makes the knotweed much more susceptible to death when atta led by the human hands on approach.;)

[Hubris]

As a few people are readily suggesting the use of glyphosate, please be very careful with this as it IS carcinogenic.

People have succumbed to horrible deaths after prolonged exposure to this stuff. Don't believe the mainstream media telling you it's "perfectly safe" bs, too.

[Harry Flashman]

crankedup said:

Environment angency have been. use trialling insect bugs which positively love to eat the sap from knotweed. Love it so much they eat nothing else! Although this little bug thrives on the knotweed thier dietary needs do not destroy the plant, but considerably weaken it. Makes the knotweed much more susceptible to death when atta led by the human hands on approach.;)

I believe that there is a bug native to Japan that helps keep the stuff in check over there. The critter doesn't live in the UK as yet.

[ozzuk]

You asked if it could impact any future sale, the answer is almost certainly yes. I've walked away from properties that have it on the boundary, and it can be harder to get a mortgage. If it was council land then often they have a management plan and this can put some lenders at ease - but as its private land it might be more of an issue. I did once offer on a property that had it - its not impossible to remove and I really wanted the house - we were even going to chop it down just to get past the survey but we couldn't agree on price so didn't matter.

Even if you treat it and its not visible, you might want to mention during any sale, better to be up front than it becoming an issue after the sale and they found out you knew.

[Andehh]

ozzuk said:

You asked if it could impact any future sale, the answer is almost certainly yes. I've walked away from properties that have it on the boundary, and it can be harder to get a mortgage. If it was council land then often they have a management plan and this can put some lenders at ease - but as its private land it might be more of an issue. I did once offer on a property that had it - its not impossible to remove and I really wanted the house - we were even going to chop it down just to get past the survey but we couldn't agree on price so didn't matter.

Even if you treat it and its not visible, you might want to mention during any sale, better to be up front than it becoming an issue after the sale and they found out you knew.

I am surprised at this, mainly because there are obviously big firms who sort out Knotweed for a fee, and come with 10 year guarantee etc. Not cheap at the £10,000 - £15,000 you hear mentioned, but it's not as if it is some alien species no one has seen, heard or treated before. It's a plant, it can be killed, and it can be killed successfully. It wouldn't instantly put me off buying a house, providing it was being dealt with properly, or I could get the money off the asking price to treat it properly.

The horror stories/general sense of unease comes from morons (like the story above) who treat it with bleach, salt, then cut it up and compost it without researching it properly.... then act horrified & cry foul when it takes over their garden.

[TeaNoSugar]

ozzuk said:

You asked if it could impact any future sale, the answer is almost certainly yes. I've walked away from properties that have it on the boundary, and it can be harder to get a mortgage. If it was council land then often they have a management plan and this can put some lenders at ease - but as its private land it might be more of an issue. I did once offer on a property that had it - its not impossible to remove and I really wanted the house - we were even going to chop it down just to get past the survey but we couldn't agree on price so didn't matter.

Even if you treat it and its not visible, you might want to mention during any sale, better to be up front than it becoming an issue after the sale and they found out you knew.

You're absolutely right. I was having a beer with my neighbours last night in the garden, and one of them said his brother actually reversed a house purchase because the seller had lied on the survey; there was knotweed in the paved back-yard less than 5m from the back wall of the house but he'd just chopped it back to ground level, covered it over and declared that there had never been an issue with knotweed.

The current plan is to try and catch the landowner when he's at home, have a word with him and see if he's willing to get some professional in to do it. Apparently he used to have the land cleared every so often by some landscaping firm, but hasn't done so the past 5 years or so. We don't really want it being public knowledge, so if he's not helpful, myself and my neighbour are going to get the heavy duty weedkiller, and make a start on it, as some of the posters have described. I need it at least under some control because we're hoping to move house later this year.

Again, thanks for all the advice, much apprecited.