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  • Spotted wing drosophila

    Or Drosophila suzukii.

    Bit of a rant/call for sympathy+suggestions:-

    Over the last four or five years, the usable crop from my dwarf morello cherry tree has dropped from 10-15 lb to nothing. The SWD grubs infest every single cherry. While one can drown the little sods in rum (Rum pots are the normal end result of the crop apart from an occasional crumble), it's got to the point where even that is a loosing battle.

    This year I set up a couple of traps, the attractant is cheap red wine and vinegar. For two weeks, they've caught a few midges, but nothing identifiable. This week there are a significant number of ones with spotted wings. It's possible (probable?) that the previous takes caught only females and not the, spotted, males.

    I have bought a quantity of industrial deltamethrin and will start spraying it weekly tomorrow. I'd like to alternate it with something else to avoid resistance buildup, but the only other thing I can think of is neonics, and they are extremely toxic to birds. Need to keep looking for an alternate.

    I also need to talk to the next door neighbours, because they've got an allegedly dwarf (20 foot high) Stella desert cherry. I think they've stopped getting useful crops from theirs as well. Theirs'll need spraying as well.

    I probably need to look into investing in a vast amount of fine mesh to envelop the tree in.

    I'm wondering if it might not be easier to grub the tree out and just buy cherries from the shop. It'd be a lot cheaper.
    Location:- Rugby, Warwckshire on Limy clay (within sight of the Cement factory)

  • #2
    I've never heard of this critter so I looked it up. This piece provided a lot of info - American of course - apparently the best trap is apple cider vinegar and sake. As the little blighters don't like sunshine, can you prune the tree to let in more light, and prune back anything else that overshadows it?

    http://ipm.ucanr.edu/PDF/MISC/2014_C...Drosophila.pdf
    Last edited by mothhawk; 14-05-2022, 11:41 AM.
    Location - Leicestershire - Chisit-land
    Endless wonder.

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    • #3
      Gave it the first spray yesterday

      Just had a thought:-


      If I get some mesh that's suitable for keeping the birds (great tits and robins) out, then I can still hit the SWD with neonics every now and again to try to avoid resistance. That seems better than using the very fine 0.25 x 0,8mm mesh that's needed to keep the SWD out (or in?). Don't have to worry about bees, since flowering is well over.

      Wonder if I'll manage to get a crop this year!
      Last edited by Mark Rand; 15-05-2022, 01:17 PM.
      Location:- Rugby, Warwckshire on Limy clay (within sight of the Cement factory)

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      • #4
        Mark, it is illegal to use neonicotinoids in the UK, especially in gardens. I have to wonder where you got hold of it (if you have). If you spray it, it will go not only on your trees, but blow onto the ground and surrounding area.

        Sugar beet growers have been granted emergency use this year on seed, and have to follow precautions which are, namely, "a ban on any flowering crops (or ground cover) in the soil where treated seed is used for a period of 32 months following the crop planting and the use of herbicides to prevent flowering of any weeds and wildflowers. "

        Neonics are just too toxic. Please, please don't use it.
        Location - Leicestershire - Chisit-land
        Endless wonder.

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        • #5
          How big’s your tree Mark,could you make a few sleeves with fine netting instead of covering the whole tree?
          Last edited by Jungle Jane; 15-05-2022, 04:05 PM.
          Location : Essex

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          • #6
            Originally posted by mothhawk View Post
            Mark, it is illegal to use neonicotinoids in the UK, especially in gardens. I have to wonder where you got hold of it (if you have).

            <SNIP>

            Neonics are just too toxic. Please, please don't use it.

            Acetamiprid is still available and licenced for uses such as SWD.

            https://www.rhs.org.uk/advice/pdfs/p...-gardeners.pdf

            Originally posted by RHS Pesticides for home gardeners
            a) Acetamiprid
            A broad spectrum, systemic and contact action pesticide for use as a foliar spray on ornamental plants.
            Some formulations can be used on tomato, aubergine, pepper, potato, lettuce, apple, pear, cherry and
            plum. Also as a compost drench on container grown ornamental plants, primarily against vine weevil
            grubs. This pesticide also controls aphids, whitefly, scale insects, mealybugs and thrips. The spray
            formulations can also be used against red spider mite, lily beetle and caterpillars. Sprays containing the
            fungicide triticonazole also control mildew, rust and blackspot on roses.
            Sprays BugClear Ultra concentrate
            BugClear Ultra Gun RTU
            RoseClear Ultra concentrate (+ triticonazole*)
            RoseClear Ultra Gun RTU (+ triticonazole*)
            Compost drench BugClear Ultra Vine Weevil Killer
            The precautions which are needed are to ensure that there are no pollinating insects (==no flowers) and to exclude birds, since neonics are very toxic to avians, but not mammals.

            I'd far rather see such chemicals used responsibly and with appropriate precaustions in small scale use instead of being sprayed over thousands of acres of oilseed rape when it's about to flower...

            The abrogation for the use of three, named, neonics on sugarbeet seeds is due to the risk of aphids spreading the beet yellows virus amongst sugarbeet seedlings and potentially reducing the crop between a predicted 20% and a theoretical maximum 50%. My crop had been reduced by 100% in the last few years! The only alternative is to grub the tree out and give up.
            Location:- Rugby, Warwckshire on Limy clay (within sight of the Cement factory)

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            • #7
              Originally posted by Jungle Jane View Post
              How big’s your tree Mark,could you make a few sleeves with fine netting instead of covering the whole tree?
              Unfortunately, one would need to sleeve almost all the previous year's growth, which is where Morello cherries flower and fruit to get a decent crop. I looked into commercial sleeves last year and was shocked at the price (Ok for figs and pomegranates maybe, not for cherries!). The shed behind the tree is about 3.5m tall, so the tree is touching 4.5m from the ground. It wouldn't be a problem to tie the netting around the lower trunk or to prune the top branches to fit the netting available.

              One advantage of the shed when spraying with the pyrethrin yesterday was that I could climb up to the shed roof and spray most of the tree and some of next door's from above.
              Location:- Rugby, Warwckshire on Limy clay (within sight of the Cement factory)

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              • #8
                mothhawk, have a look at this: https://en.wikipedia.org/wiki/Acetamiprid

                One presumes you had the neighbour's permission to spray their tree, Mark, and that the spray didn't fall on any other plants bees might be interested in or insects that birds might eat.
                Location: north-east Spain, where the sun is too hot, the rain too torrential, the hail too big, the wind too windy and the snow too deep. Last frost: usually mid-April, sometimes first week in May. First frost: mid-October.

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                • #9
                  Second spray of deltamethrin/pyrethroid today. Looks like I might have to grub the tree out in the end anyway. Note the little spot, that's the calling card of the SWD (photo taken with a magnifying glass in front of the phone):-
                  Last edited by Mark Rand; 21-05-2022, 07:36 PM.
                  Location:- Rugby, Warwckshire on Limy clay (within sight of the Cement factory)

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