Panic! Panic! Japanese Knotweed!

[tingers]

Hi everyone

I've only recently started gardening - literally a month ago. I have a tiny garden which is covered in gravel but have recently planted things in pots, been growing seeds and really enjoying watching everthing take shape...

But I dug out a couple of flower beds recently and found a horrible weed infesting the soil. My neighbour said it was Japanese Knotweed, and I looked it up - it seems to be.

What should I do? I can't pull it out because the rest of the garden is gravelled over. But it's underneath everything (including our decking) and I worry it might cause damage to the house, or start to invade other people's gardens. Am I over-reacting or do we need to pay someone to come, dig 10ft down and use horrible chemicals to get rid of it all? From what I've read, all methods of eradicating it are so brutal!

(I've tried to upload a picture to my Gallery but it doesn't seem to be working...)

[Stinky Bob]

Glyphosate (multiple applications), I think has the only chance against it if you go down this route. Be aware though that if you attempt to dig it up it cannot be tipped at the local dump (even the soil it was in), it has to be disposed off at a licensed landfill site. Unfortunately it will spread like wildfire and yes it has the potential to go through concrete. Its a council and building developers worse nightmare. You may want to contact your local council, and see what they suggest as some council do have information on their web sites about it, Cardiff and South West Councils in particular.

Good Luck

PS The young spring shoots can be cooked and eaten
PPS Welcome to WAB by the way

[tingers]

Thanks for that Bob. So, are you saying that I'd have to rip up all the liner and even the decking, get rid of a whole garden's worth of gravel to expose the weeds and then use the Glyphosate? I take it I couldn't just use it on the bits that I've exposed in my beds? I have a vain hope that if I injected something into the roots at one or two points, it would spread to the bits I can't see. But is that just a foolish hope!?

[Meta menardi]

Glyphosate is a relatively soft herbicide and the fact that it moves through the plant is very useful for rampant weeds. You have to make your own mind up about this, but the knotweed will not wait. If you do decide to use Glyphosate (read the labels carefully to check that it is the active ingredient in what you buy, if you do), careful reading of the methods of use will help minimize the amount you have to use. If it is not hitting the plant you want to kill, you are wasting it.

Best of luck, and don't be put off gardening, even if it is starting with a problem.

[Jim Ford]

Glyphosate (Monsanto 'Roundup') is the stuff to use. Spray it on every time a new shoot pokes its head above ground. The plant absorbs the glyphosate and it will eventually kill the whole planet - roots and all.

It's also worth remembering that plants need sunlight to photosynthesise. If you keep relentlessly cutting the top growth of a weed off as soon as it appears, it will weaken and die. Keep at it - don't even let a tip of green show. A dutch hoe is good for this. If it's a small garden it should only take a few minutes a day to 'tickle' round it.

Weeds can't grow faster than you can cut them down - but they're sneaky, they grow when you're in bed, at work and on holiday! So be vigilant.

Jim

[Meta menardi]

Originally Posted by Jim Ford

Glyphosate (Monsanto 'Roundup') is the stuff to use. Spray it on every time a new shoot pokes its head above ground. The plant absorbs the glyphosate and it will eventually kill the whole planet - roots and all.

It's also worth remembering that plants need sunlight to photosynthesise. If you keep relentlessly cutting the top growth of a weed off as soon as it appears, it will weaken and die. Keep at it - don't even let a tip of green show. A dutch hoe is good for this. If it's a small garden it should only take a few minutes a day to 'tickle' round it.

Weeds can't grow faster than you can cut them down - but they're sneaky, they grow when you're in bed, at work and on holiday! So be vigilant.

Jim

Jim is 100% right in his comments, the only thing I would add to his comments is that active Photosynthesis is required to spread the Glyphosate through the plant. Some active growth, then a spray will work, followed a short time later by some good hoeing will help.

[jayvee64]

After reading this thread, I've been searching for pics of this weed, especially pics of the young plant so I could identify it if it started to grow in the garden. It's a frightening thing isn't it! I always find it amazing how some plants/weeds are able to grow and spread like that. Are there parts of the country where it's more prevalent or does it grow everywhere.?
Best of luck with getting rid.

[Cowgirl]

Hi there, just to add as well, if you can' use a sprayer cos there's other plants around paint the glyphosate directly onto the leaves. Keep at the @%$*@~*!

[Stinky Bob]

Originally Posted by Jim Ford

Glyphosate (Monsanto 'Roundup') is the stuff to use. Spray it on every time a new shoot pokes its head above ground. The plant absorbs the glyphosate and it will eventually kill the whole planet - roots and all.

It's also worth remembering that plants need sunlight to photosynthesise. If you keep relentlessly cutting the top growth of a weed off as soon as it appears, it will weaken and die. Keep at it - don't even let a tip of green show. A dutch hoe is good for this. If it's a small garden it should only take a few minutes a day to 'tickle' round it.

Weeds can't grow faster than you can cut them down - but they're sneaky, they grow when you're in bed, at work and on holiday! So be vigilant.

Jim

One caveat to this though is that JK can reproduce from the tiniest bit of green matter (about 0.7gm I think) so if you hoe or cut down you need to make sure that you collect everything and either dispose off legally or burn it. One trick you can use is to fix a small plastic bag to the end of the growing tip and spray your weed killer into this, this may help when you cannot apply a spray application because of nearby plants or near water etc.

[Cotham Marble]

Originally Posted by Stinky Bob

One caveat to this though is that JK can reproduce from the tiniest bit of green matter (about 0.7gm I think) so if you hoe or cut down you need to make sure that you collect everything and either dispose off legally or burn it. One trick you can use is to fix a small plastic bag to the end of the growing tip and spray your weed killer into this, this may help when you cannot apply a spray application because of nearby plants or near water etc.

The need to ensure complete 'hygene' when dealing with JK is absolute, it is only the plant's incredible capacity to vegatatively reproduce that makes it a problem as it seems unable to reproduce by seed in the UK. However I'm concerned that all this advice is being given, without a definitive identification of what the plant in question actually is and Tingers is being encouraged to take all sorts of drastic action on the basis of what may or may not be a serious problem.

If it is JK, then Tingers can rely on the gravel and liner, and also the decking as suspressing agents, so long as all points of break through are treated repeatedly with glyphosphate, as without the capacity to photosynthsise the roots will eventually die - but perhaps not for a decade ! The problem though is that if there is a well established root system, (and it sounds as if the use of gravel and decking may have been employed to cover up something that was known to the previous occupant) then there's every likelihood that the infestation will simply spread beyond the property boundaries. I think that if the gravel and decking are going to remain in place, then unless it's already been done, deep trenching (double spade depth at least) along the property boundaries and insertion of a vertical membrane will be necessary to keep the JK contained.

But first - get a definite identification.

CM