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Japanese Knotweed - one shoot!

edited 30 November -1 at 1:00AM in Greenfingered MoneySaving
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SandraScarlettSandraScarlett Forumite
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edited 30 November -1 at 1:00AM in Greenfingered MoneySaving
My neighbour was watering my garden whilst I was away and has told me he has discovered Japanese Knotweed at the bottom. I had no idea what it looked like.

I've phoned several companies and have had eye watering quotes, just to carry out a survey, and just one has said it was free and they are coming next week.

Once I looked at the area closely, I could see there is just one shoot and I wondered if there is any way I could treat this myself.

Any advice would be gratefully received.
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  • donmaicodonmaico Forumite
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    My neighbour was watering my garden whilst I was away and has told me he has discovered Japanese Knotweed at the bottom. I had no idea what it looked like.

    I've phoned several companies and have had eye watering quotes, just to carry out a survey, and just one has said it was free and they are coming next week.

    Once I looked at the area closely, I could see there is just one shoot and I wondered if there is any way I could treat this myself.

    Any advice would be gratefully received.

    you could try using a Glyphosate-based weedkiller such as Roundup Tree Stump & Rootkiller. Spray the leaves and canes well and keep an eye of it as you will need to do further reprays .It can take 3 years to get rid of the stuff so prepare for regrowth next spring when it will look somewhat different
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  • GrenageGrenage Forumite
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    Are you sure it's knotweed? I'd also use a Glyphosate solution; might be worth reading up on the best time to apply.
  • daveyjpdaveyjp Forumite
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    First confirm it is knotweed. If it is one shoot there will be far bigger shoots nearby.

    Take some photos, upload and share the link here.

    Anyone who says they are a 'specialist' will probably rip you off so be careful. From experience. "specialist" quote, £12,000, local grounds maintenance company £500.

    If it is knotweed don't do anything for 2-3 months.
  • DavesnaveDavesnave Forumite
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    Look around at neighbours to see if it may have originated there, and get a positive ID , because there are plants that look like knotweed, and aren't. If a neighbour has it, it's important to get them on board.

    You have plenty of time to read-up on treatment if it is. There are no magic formulas and you can do this yourself with such a small amount.

    As davey suggests, don't be panicked into signing-up to an expensive treatment programme and expect any 'free' survey to be as pleasant as the average double-glazing sales pitch!
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  • SandraScarlettSandraScarlett Forumite
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    Thank you for all the helpful replies. Alas, I'm not able to upload photos, but the neighbours have confirmed it is knotweed, though they, as yet, don't have any.


    A friend has told me he treated his in June and September, with a product he bought some years ago, which is apparently a type of "Commercial Strength Glyphosate", and isn't available now.


    He had a few stems, as opposed to my solitary one, and treated his by digging down about one foot, burning the stems, inserting a metal cylinder (he suggested a baked beans can, washed thoroughly and both ends removed) and pouring this stuff down, then covering the hole with a large paving stone.


    He then did this for about 3 years, after which nothing else appeared. Other people present during this conversation, all nodded in agreement, and some mentioned other products that they still had in their sheds, that you cannot buy now.


    What do you folk think?
  • DaftyDuckDaftyDuck Forumite
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    No, not the correct technique. Keen gardener, hobby farmer with (ex)knotweed problem, and sometime Bayer SME scientist ( now owners of Monsanto). Mind you, I have a different area of expertise...

    Glyphosate is pretty well instantly inactivated by contact with soil. Spectacularly so. Smother a pair of plants with glyphosate, then chuck a couple of handfuls of soil on one, and only one dies. With your friend's technique, the glyphosate is not taken up by the growing part of the plant, and is pretty much inactivated instantly anyway. Tin? Stone on top? Ha, he's just hiding his folly from others!

    Correct technique is to wait until growth is maximal, usually after August. Either spray twice three days apart at normal dilutions, or inject directly into hollow stem, at 1.5X concentration.

    Given you have but one stem, I might be tempted to carefully dig it up, but we are talking Time Team style, slowly with a hand trowel at most. You need to follow all the root back. You will still need to glyphosate before doing this, and wait a month plus after that before excavation, but it might help.

    If it is away from your property, and not coming in from the neighbours, I would try treating it yourself.
  • DavesnaveDavesnave Forumite
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    He then did this for about 3 years, after which nothing else appeared. Other people present during this conversation, all nodded in agreement, and some mentioned other products that they still had in their sheds, that you cannot buy now.


    What do you folk think?
    There is no 'commercial strength glyphosate' one cannot buy now. I've recently become licensed to buy the strongest type, but I've been buying it over the internet for years without any questions being asked! The 360g/litre stuff is fine anyway.

    Dafty is also right about technique.

    The weedkiller many of us shouldn't have in our sheds is probably Sodium Chlorate, which was withdrawn in 2011. I'm not sure that would be any more effective though.
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  • SandraScarlettSandraScarlett Forumite
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    Given you have but one stem, I might be tempted to carefully dig it up, but we are talking Time Team style, slowly with a hand trowel at most. You need to follow all the root back.


    Do you mean I should dig all around the stem with a hand trowel?


    You will still need to glyphosate before doing this, and wait a month plus after that before excavation, but it might help.

    If it is away from your property, and not coming in from the neighbours, I would try treating it yourself.


    It's very near the fence, and the adjacent new neighbour, who is not the friendliest, has only recently started digging over his garden. I asked if he'd come across this knotweed, he lifted the fence panel to look at my solitary shoot, and denied he'd dug up anything like that. But he would say that, wouldn't he!
  • DaftyDuckDaftyDuck Forumite
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    The stem will have a long yellowish-centred fibrous root that may travel horizontally several feet. Even a fingernail size fragment will have the potential to grow. You must use glyphosate first. Then gently dig out all the root a month later, when it has been mostly killed.

    And your neighbour - who appears to have just dug over his garden - would say that, wouldn't he! That doesn't mean you're did come from him, but it does mean you need to stop it spreading to him....
  • edited 14 June 2019 at 6:22PM
    SandraScarlettSandraScarlett Forumite
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    edited 14 June 2019 at 6:22PM
    Thank you for all your replies. I've emailed the person coming this week to confirm I don't have to pay for the visit (want something in writing), and as the company's cost is likely to be mega expensive, I'll try the DIY method.

    Can I just confirm that I should wait till August to treat this?

    And then I should spray everything with glyphosate?

    After which I should wait a few days, and then spray again.

    Then wait a few weeks, and then try digging it up with a hand trowel.

    I must have some very sick slugs nearby, as a lot of the leaves appear to have been partially eaten!
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