Getting rid of Japanese knotweed

I need help! how to get rid of Japanese knotweed - I have been told to put deisel on the crown and pour it down into the stalks but this sounds drastic, wont the soil be damaged as well - look forward to any suggestions.

 

I think you may need to get a specialist in. Where is this knotweed? Is it in your garden, near your house?

While you're deciding on the long term solution, I'd recommend you start spraying it regularly with RoundUp. Buy the concentrated stuff that you dilute, otherwise it will get very costly because you'll need to do many treatments.

The diesel idea is an old trick I've heard before. I've never heard it from someone who's horticultural advice I'd trust though. I can't see how it could even work. The plant isn't going to take the diesel down to its roots, so it would just do superficial short term damage I expect. Whereas glyphosate goes right down to the roots to kill the plant dead, although I expect it will take a while in the case of knotweed.

 

There was a segment on this week's Beechgrove garden about this.
It involved injecting the stems with some chemical.
Look at their website.

 

Blimey, this stuff is from outerspace !!! I had it in the garden of my last house. I was managing to keep the big stuff down BUT, the problem is when it starts forcing it's way through cracks in concrete, then I had a problem getting at it.
With a constant barrage of weed killer I managed to keep most of it at bay. But if I let up for a week or so it would soon rear it's ugly head.
You have some good advise already so I'm sure with the help of these guys you'll make some headway.
Gazania.

 

I've been watching some shooting up locally that was professionally "killed" by repeat treatment a few years ago.
I say professionally treated as it was on council land and they killed everything else around the area with repeat spraying.

They stopped spraying a couple of years ago.
I think its making a come back.

Dont think I would use diesel, nasty stuff when used on the soil.

 

Thank you for your reply - it is at the bottom of the garden - not near the house, I have checked the drains but they seem clear. It has spread from next door (their garden is neglected and is now wild) I will use the roundup first but might resort to the deisel as well. It is my daughters house and she has 2 cats - I will uncover the crowns and treat and then cover up with patio liner to prevent the animals from getting poisoned. The plan is to treat it every 2 weeks - I will let you know how I go on. Thanks again

 

I know its not really a welcome thought but if it has spread from next door then I believe you are well in your rights to take them to court as part of the law that governs pernicious weeds is that you are responsible for its spread to neighbouring properties

Posted on the go.

 

Don't use the diesel option. Apart from the fact that your garden will stink if you do, and it will wipe out all the good little creatures living in the affected area, it will also significantly reduce your chances of beating it.

Glyphosate, the active ingredient in RoundUp and many other systemic weed killers, requires that the plant is actively growing. It sound counter intuitive, but the more healthy the target plant is, the faster glyphosate will kill it. Glyphosate is absorbed by the foliage, and is carried down into all parts of the plant. The science is over my head but the simplest (probably slightly inaccurate) explanation I've seen is that it effectively puts the plant into reverse, causing nutrients to leave the plant via the roots which in turn causes the plant to starve to death. If any parts of the plant are damaged or poorly, the glyphosate may not be carried through those parts of the plant, so they can escape the poisoning and go on to regenerate the plant.

It may be worth make some discrete enquiries to the council about what to do. Japanese Knotweed has strict controls laws. It is essential that you dispose of any parts of the plant appropriately. You can't just stick it in the green waste bin and I don't think you can even transport it without a permit or something so I don't think you can even take it to the tip. I think you have to burn it on site, but I'm not sure so worth checking.

 

I read a thread recently where a guy had a japanese knotweed prob, and he sorted it using glyphosate or roundup or similar but he used it undiluted ...

I am sure I read it on this forum, but cannot find the link?

 

I think this is the link you were looking for Dim:-
http://gardenerscorner.co.uk/forum/threads/knot-weed-terror.37957/page-3#post-528824

 

Thanks for that, it has been really helpful - I am off to B & Q tomorrow. I will have a word with the neighbour and offer to treat his patch and we can burn the dead crowns etc. i dont really want to be going to Court at my age so if i am nice to them they might co-operate.

 

Hi there madchapman

Don't chuck diesel around and don't panic because it won't help!

One of the many problems with knotweed is that any little broken piece of material which you ignore can quickly make a new plant. This means that digging out roots and burning them can be counterproductive, because you will always leave bits of root in the ground which will regenerate. In fact, the plant positively thrives on this sort of disturbance. It's better to leave the plant alone and zap it with weedkiller.

My next-door-but-one neighbour inherited a thriving patch of Japanese knotweed. It started to spread under the fence to my direct neighbour's garden. When she had to go into a care home and the garden became neglected, I had nightmares about the stuff getting into my flowerbeds. So I'm afraid I trespassed a bit and zapped the stuff with weedkiller. I can't remember which one but it was just an ordinary brand - Resolva, I think. I just kept spraying and spraying and spraying;fortunately there was nothing much else in that part of the garden which might have got damaged by it.

Well, two years on and - touch wood - I've yet to see those sinister shoots make a reappearance. I might be being too optimistic; it is incredibly difficult stuff to kill. But I have certainly stopped it in its tracks for a bit.

I remember Pete saying that wild patches that are left alone don't seem to spread as much as you might fear; I think he's right. Disturbing knotweed is the worst thing you can do. Leave the roots alone, don't try to dig them out - instead, use a systemic spray which will get taken down to the roots and hopefully kill them. The other thing is that when professionals tackle knotweed they are extremely careful not to transport bits of it on clothing or shoes, because you can unwittingly spread it around.

Shame we can't eat the stuff. We could cure world hunger at a stroke.

PS I read a magazine article a while back which suggested an interesting method of control. Cut the tops of the shoots off, leaving the hollow stems. Make yourself a d-i-y funnel out of a drinking straw and pour weedkiller into the stem. Cover with a plastic bag secured with wire closure et voila! I haven't tried it but it sounds worth a go.

 

Has it been released into the wild yet? I know there are plans to do it but I don't know what stage they're at.

 

The trouble is, the bug might get rid of the knotweed but then, if it works, we might need something to get rid of the bug!

 

Yep. You'd think us human sorts would have cottoned on now that we should be careful what we do to the natural balance. A few examples that spring to mind:

* Rabbits imported from the middle east for their meat and fur = A pest so serious there are laws specifically about their control

* Hunt larger predators to extinction in Britain to protect livestock = Rabbit and deer populations explode out of proportion and eat everything.

* A pretty plant spotted by some rich dude's scouts and brought back to Blighty = Japanese Knotweed problem so bad someone decided to introduce a new bug to try to control a previous introduction.

It would be funny if it wasn't so serious.