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Vine weevil grubs in containers!

CraighBCraighB Posts: 758
in Problem solving
Hi guys,

I treated my containers with vine weevil killer (bug clear vine weevil killer) last September but I checked at the weekend and there are active vine weevil grubs in a few of the containers! They haven't completely killed the plant but some parts of it came away when I pulled it.

Is it worth drenching them now with the killer to try and save the plant?

Thanks
Craigh

Posts

  • BobTheGardenerBobTheGardener Posts: 11,385
    edited February 2020
    Depends on the plant.  If something like heuchera (just a guess based on 'bits of it coming away'), I would dig it up, wash all soil from the roots and repot into fresh mpc.
    How you treat the containers is up to you, but it sounds like the pesticide has been washed through or the weevils are resistant to it, so would remove and treat any wanted plants as above then wait for the weather to warm up before applying nematodes.  VW killer is systemic (taken up by the plants) and can then get into insects by various paths, so I've stopped using it.
    A trowel in the hand is worth a thousand lost under a bush.
  • CraighBCraighB Posts: 758
    Hi Bob,

    It's a hardy geranium and clumps of it have just come away but some are still anchored Into the compost really well.
  • Bee witchedBee witched Posts: 1,295
    Hi @CraighB

    Good advice from Bob.
    I've also found some weevil grubs in pots of succulents in my greenhouse. I'm assuming other plants over-wintering in there could be affected. So I'll be using nematodes once the soil temperature is 12C .... meantime I'm cleaning and re-potting as Bob has described.
    Bee x
    Gardener and beekeeper in beautiful Scottish Borders  

    A single bee creates just one twelfth of a teaspoon of honey in her lifetime
  • CraighBCraighB Posts: 758
    I will do that. Luckily I do have some of the same plant in the ground that don't seem to be affected so if I do lose the one in the container I have a back up :)
  • madpenguinmadpenguin Posts: 2,543
    The problem I find with nematodes is you have to keep the soil moist for some time (not good with succulents!) and you need to make up a largish amount plus the soil has to be a high enough temperature.
    Not really convenient if you only want small amounts.
    “Every day is ordinary, until it isn't.” - Bernard Cornwell-Death of Kings
  • CraighBCraighB Posts: 758
    I didn't think vine weevil grubs started chomping on plants this early in the year? Or is it because we have had a mild winter so far?

    I did use nematodes on the borders a few years back for slugs and snails and I have to say it worked really well! Might try it next time for vine weevil as they seem to sell 2 different sorts. One for slugs and snails and then another pack for vine weevil.
  • wild edgeswild edges Posts: 10,497
    edited February 2020
    Rik56 said:
    CraighB said:
    I didn't think vine weevil grubs started chomping on plants this early in the year? Or is it because we have had a mild winter so far?



    I think the mild winter has woken up a lot things a bit early. I was surprised when I checked my containers (and I've not checked them all...it got a bit windy!)
    The grubs start hatching in the autumn and I've been finding plenty already this year. I've also found quite a few tiny ones that have just hatched. It's been fairly mild but it's safe to assume they can be in your pots all winter no matter how cold. I think there's confusion because we're told to use nematodes in the spring but that's to do with the soil temperatures for the nematodes rather than the VW grubs.
    If you can keep your head, while those around you are losing theirs, you may not have grasped the seriousness of the situation.
  • simondlangley43simondlangley43 Posts: 1
    I was about to order nematodes when I saw this article that says they also very quickly kill bees - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4655097/ so looking for other methods.
  • kwadskwads Posts: 14
    I treated my containers just over a week ago with nematodes.  I've just checked them now and there are still lots of eggs but no grubs.  Does this mean the nematodes have worked?
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