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Vine weevil: plan of action needed!

Rose121Rose121 Posts: 132
in Plants
I've just tried to repot some strawbs, and found what are definitely vine weevil grubs in the soil. I've aborted the repot, and now need a plan of action. I'm thinking:
1) Get rid of all the old compost, and repot in new
2) Treat the whole garden, but particularly the pots, with nematodes next autumn, which seems to be the appropriate time of year

What else should I do? Should i junk the plants and get new strawbs to avoid any hiding in roots? I luckily have to repot all my other potted plants/shrubs this winter, as I'm putting in water reservoirs so I'll be able to check how many are affected. i want to nip this in the bud before it becomes an ongoing problem.

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  • FlinsterFlinster Posts: 883
    For ornamental pots you can buy a drench which is applied in April I think (bug clear vine weevil) but not for edibles. It kills the grubs and the weevils as it’s systemic. I’ve bought some for mine as I’m in the same boat! Going to try nematodes- think you apply them in late spring and autumn as it breaks the life cycle (larva pupate in spring).
  • Allotment BoyAllotment Boy Posts: 6,774
    I don't think Provado is available anymore as it contained neonicotinoids (not sure I have spelt that correctly). I too have used a combination of nematodes for edibles & the Bug clear for non edibles. 
    AB Still learning

  • Rose121Rose121 Posts: 132
    Thanks all - I'll get the drench for my other pots, which don't contain edibles. Little blighters! Grit on top is a great tip going forward. 
  • LiriodendronLiriodendron Posts: 8,328
    You can use Bug Clear ultimate vine weevil killer on ornamentals - but please consider NOT doing so!  It's been reformulated so it no longer contains Imidacloprid, one of the withdrawn neonicotinoids shown to be very harmful to bees.  But it does contain Acetamiprid, another neonicotinoid said to be safer, but tests in America seem to show that although it isn't as bad as some, it still harms bees.  Neonics are designed to disrupt the nervous systems of insects.  Slugs eating plants treated with neonics are unaffected, but ground beetles eating those slugs are killed by the chemical.
    Since 2019 I've lived in east Clare, in the west of Ireland.
  • gardeninglily1gardeninglily1 Posts: 424
    @Liriodendron what would you suggest is the best plan of action? I had a beautiful heuchera in a hanging basket that flowered it’s socks off last year. But over the winter it’s looked limp and when I had a closer look today it’s infested with the little blighters  :o I have got a couple of others in baskets too and some in the ground and they all seem to be ok so far. But I would like to be sure they don’t go the same way. Thank you 
  • LiriodendronLiriodendron Posts: 8,328
    edited February 2019
    @gardeninglily1 - I reckon it's important to be vigilant, and to know which plants are likely to be affected, so that if you notice they're not looking quite right you can have a little dig in the soil and see if the dreaded vine weevil are around.  In my garden, in the soil rather than in pots, most plants can cope with a few vine weevil grubs without suffering, because their roots spread wide enough.  The exceptions for me are primulas (some sorts more than others), cyclamen and heucheras.  I target those with nematodes twice a year, and squash any adult weevils I find in the garden.  Look out for notched leaves, too, especially on rhododendrons and other evergreens, which are eaten by adult weevils.  They are around mostly at night, and squash with a satisfying "pop"... sorry...

    My experience is that it is possible to get on top of an infestation using nematodes but it takes time and persistence.  

    Plants in pots and baskets are more vulnerable because their roots don't spread so far - and because the grubs seem to prefer peat-based compost.  But at least you can be sure you've treated all the compost in a pot with nematodes, and they do work, provided you follow the instructions.  It does need to be warm enough for them to be active though.  They're expensive, but maybe worth the expense if it means you don't have to replace your heucheras...

    Good luck!
    Since 2019 I've lived in east Clare, in the west of Ireland.
  • MayLaneMayLane Posts: 203
    I was pulling off 70 - 100 from plants in the summer. I am convinced they have been attacking over winter.

    Ate my dogwood s completely. My red robins, fatsias and magnolia look tatty. Treated with nematodes during autumn and have some on order for sprint but am worried already. The whole estate has shrubs in front gardens that have been eaten by them.
  • gardeninglily1gardeninglily1 Posts: 424
    Thank you @Liriodendron - I only moved some of my  heucheras into baskets last summer - and they flourished!! I thought I was safe but they didn’t waste much time  :s I will definitely get some of those nematodes next month.  I bought some for slugs last year but prob wasted my money because it was September - is best time in the spring? @MayLane Ive never had a problem with fatsia or camellias-sounds like you have the conditions they like in your garden - I’m on the coast and my soil is quite sandy. 
  • FairygirlFairygirl Posts: 55,117
    I think MayLane's situation is a highly unusual one, and not what most of us would experience.
    I wonder if there are certain soil/climate conditions in your area which are causing that kevel of infestation, @MayLane?
    Rinsing/removing all the affected soil/compost and chucking the grubs out for the birds will put paid to them for now, and then replanting in fresh soil,  and then it's a case of using an appropriate method afterwards.
    Nematodes seem to be the best method nowadays, but as Liri says, vigilance is necessary, and regular squishing of adults helps reduce the future population. Healthy shrubs can shrug off some minor damage, so they are rarely affected badly, but it's certainly things like Heucheras in pots which succumb quite frequently. Some sedums and a few other things too.
    I had a sedum which brought them in, and I'll need to treat my raised beds this year. 
    It's a place where beautiful isn't enough of a word....



    I live in west central Scotland - not where that photo is...
  • Bee witchedBee witched Posts: 1,295
    Hello @gardeninglily1,

    Whilst you are waiting for the temperatures to perk up so you can use nematodes .... you might want to try something that I did last year. 
    I found lots of grubs in pots of strawberries. I lifted the plants, washed off as much soil as I could, and submerged them in water for 48 hours .... giving them an occasional swish.
    There were a few grubs which floated off and were well and truly dead (they are sneaky b*ggers but haven't mastered swimming yet!)

    I repotted the plants which were all OK.

    Worth a try .. Bee x
    Gardener and beekeeper in beautiful Scottish Borders  

    A single bee creates just one twelfth of a teaspoon of honey in her lifetime
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