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Cabbage stalk weevils

Has any knowledge/experience of cabbage stalk weevils? The little blighters arrived in their hundreds, I think from a seemingly untreated oilseed rape field about 1/2 km away, about 4 days ago. I have heartbreakingly ripped out all of my brassicas except for the cavolo nero that they seem not to go for at all. All the plants are at the skip.

With no brassicas, they seem to be settling down among the nasturtiums. I have no idea if this is temporary or if they will be happy there for the foreseeable. I could rip out the nasturtiums as well but would they then just move on to the next plant? 

I'm hoping the field will be harvested in the not too distant future, at which point I'm expecting an massive influx of displace weevils. 

Does anyone know what, if anything, I can do other than swish them? And pray that other  veggie gardeners nearby - there are loads - are aware and trying to deal with it as well, otherwise they will presumably just breed away happily.

I can find very little information online except for farmers where the advise if zap away with chemicals, which aren't available to individuals even if I did want to use them, which I don't.

It was all going to well, the garden is starting to look fab, and now this. It's a real kick in the guts.

Posts

  • DovefromaboveDovefromabove Posts: 88,147
    My understanding is that they damage the seed pods and seeds rather than the rest of the plant … hence the problem for oilseed rape farmers. 

    What are they doing to your plants?

    Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.





  • NormandyLizNormandyLiz Posts: 788
    Munching away. My reading is that they damage the stems of the plants to lay their eggs, which they weaken the plant from within, but also that the adults then feed after emerging, i.e. now. They definitely like cauliflowers, that's when I noticed them, grazing away and causing a fair bit of damage even in one day. You can also see chewed leaf.

  • LynLyn Posts: 23,190
    I’ve still got some of my spring green plants in the GH,  they’ve been attacked by something, tiny little holes in the leaves and minute yellow eggs on the back.
    looks like flea beetle,  maybe small weevil? 
    Gardening on the wild, windy west side of Dartmoor. 

  • DovefromaboveDovefromabove Posts: 88,147
    Ah my mistake … apologies … I’d got them confused with the Cabbage Seed Weevils.  

    There’s a lot of weevils about. 🙄 

    Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.





  • NormandyLizNormandyLiz Posts: 788
    Not helped by me getting it wrong. Cabbage stem weevil, not stalk.

    I have inadvertently discovered a trap, just leave a bit of brassica stalk out and they're all over it. Shake into water, down the loo. I really do hate killing anything but when you've nurtured your seedling, planted with love, got all excited at the emergence of the first little cauli... to see it all go to the skip is just too much.

    @Lyn, tiny little holes could be flea beetles? And groups of tiny yellow eggs possibly small white butterfly eggs?
  • LynLyn Posts: 23,190
    The eggs are too small for the cabbage white,  minute,  I’ve pulled up the last two now for freezing.  They’ve had a good run,  had greens right through from early spring until now and plenty to last in the freezer,  just interested what they are,  the holes are very small in the leaves. 
    Gardening on the wild, windy west side of Dartmoor. 

  • NormandyLizNormandyLiz Posts: 788
    A quick update in case it helps anyone now or in the future...

    I have my fingers firmly but possibly temporarily crossed, I seem to be on top of the weevils. Interestingly, although most of my gardening friends had never heard of them, the market growers have also been blighted. They lost all their cauliflowers and broccoli, which is no joke as it's their living.

    After pulling up (nearly) all of the brassicas, I was surprised to see so many weevils still around. It turns out they love nasturtium flowers as well. Shake a nasturtium flower and you get a handful. So the nasturtiums went as well. This left me with a mere 50 or so to squish a day. I hate killing insects but sometimes it's needs must if you want to grow things.

    I did keep my 5 kalette plants. They are too precious, I couldn't bring myself to pull them out, so for about 3 weeks I just kept on checking and squashing. The weevils tended to lurk on the underneath of bigger leaves, and also curl up and fall off as a means of self defense, so there's a distinct knack to turning over a leaf while having the other hand ready to catch!

    In the end, I seem to have eradicated them. There will probably be the odd one from time to time but for the last few days I've not found one. The weather may be a factor, it's cool, wet and windy. 

    I have some cabbage, turnip, swede and sprout seedlings in the coldframe, either with the lid shut or netted with a very fine silk scarf, which has worked to keep most munchies out, and I'll wait till they're a good size before planting them out. 



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