British Columbia: Cherry Fruit Fly?

Discussion in 'Outdoor Gardening in the Pacific Northwest' started by vitog, Jul 10, 2010.

  1. vitog

    vitog Rising Contributor 10 Years

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    I've been growing sweet and sour cherries for over 30 years in Burnaby, BC, and have never had a problem with maggots in the cherries until this year. The sour cherries had a few maggots, especially if they were over-ripe; but I don't recall ever seeing maggots in the sweet cherries. Now that the Stella cherries are ripening, I noticed that some of them felt soft inside; so I investigated. They were soft because the fruit around the seed had been eaten away by some tiny, white maggots, only a couple of millimeters long and quite thin. I also noticed that the infested fruit had very small holes in the skin. The holes only became noticeable by squeezing the fruit lightly, causing some juice to appear at the surface. From what I've read on the Web, these appear to be the maggots of cherry fruit flies.

    Has anyone else noticed a recent increase in these pests, or is this a local phenomenon? It seems that most of my cherry crop is infested with them.
     
  2. wcutler

    wcutler Esteemed Contributor Forums Moderator VCBF Cherry Scout 10 Years

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  3. Natasha

    Natasha Member

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    Sorry I was in the wrong thread. this should be the right one.
    I have not seen the maggots and the rot begins under the skin. Often fruit around the stone is healthy I DID see teeny holes in the skin though. What can it be?
     

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  4. vitog

    vitog Rising Contributor 10 Years

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    Natasha, I had noticed some veins of brown flesh under the skin of my sour cherries. So I just took a closer look and found that the brown area is close to the skin; and, as you mentioned, the flesh near the stone looks OK. I didn't find any holes in the skin of the 2 cherries I examined, and I didn't find any obvious maggots either. I doubt that the problem with the sour cherries is fruit fly maggots because most of the damage they are causing in the sweet cherries is near the stone. I suspect that the brown spots in the sour cherries are due to some sort of fungus disease, but I couldn't find anything useful during a brief Google search. My sour cherries are just starting to ripen, and I'll be watching how they develop. I'll let you know if I learn anything useful. I think that a small percentage of the fruit was similarly affected during some previous years, but it wasn't a serious problem. It might just be due to the cool, wet Spring weather this year.
     
  5. silver_creek

    silver_creek Active Member

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    If you are finding tiny holes in the fruit, and maggots inside, it could be Spotted Wing Drosophila- a new pest in Washington, Oregon, and BC last year. This tiny fruit fly lays its eggs under the skin of just ripening fruit. WSU Spotted Wing Drosophila. Strawberries, raspberries, cherries, plums, peaches, hardy kiwi, grapes, and tomatoes can all be targets.
     
  6. Natasha

    Natasha Member

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    Thank you for answering! I was hoping that it was due to the weather. I must say that the cherries looked great until just before we were going to pick them. They showed the rot in a few days and then the whole tree was affected. :-( I sure hope that it is not the Spotted Wing Drosophila for that would mean that just about every fruit in the garden could be a target. Now my question is, how do I dispose of the cherries.
     
  7. vitog

    vitog Rising Contributor 10 Years

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    Silver Creek, thanks for the information about Spotted Wing Drosophila; I wasn't aware of this pest. I still think that the maggots in my sweet cherries are from Cherry Fruit Flies, but I'll be watching for signs of SWD. Their red eyes seem to be distinctive.
     
  8. silver_creek

    silver_creek Active Member

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    Cherry fruit fly is also a possibility, but from what I've heard they are not as likely in sour cherries as in sweet. SWD hits both. For the homeowner, clean up of fallen/infected fruit (disposing, not composting) helps keep down the future populations. Also hanging vinegar traps to identify- the male SWD has a spot on each wing. The SWD are also slightly larger than many fruit flies, and lighter in color, with faint striping.
     
  9. Natasha

    Natasha Member

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    This is what my cherries look like now. It is pathetic but it must be something that is well known? I'll just keep cleaning the ground underneath the tree and hope for a better year next year. :-)
     

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  10. vitog

    vitog Rising Contributor 10 Years

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    I finally got a good look at the fruit fly that is causing the problems in my sweet cherries, and it is definitely the Spotted Wing Drosophila. I could see the red eyes and the spot on each wing of the male flies. That's really bad news, because the Cherry Fruit Fly has only one generation each year, but the SWD has many. Anyway, I discovered that my compost bin was full of them because I've been tossing damaged cherries in there. I've lost my entire crop of sweet cherries, about a hundred pounds, to these pests. It took all day to remove every cherry from 2 trees. After picking, I cooked the cherries to kill the maggots and then buried them all in the garden.

    Natasha, the cherries in your last photo are infected with Brown Rot, which is a common secondary fungus infection after the fruit is damaged by the fruit flies. Interestingly enough, my sour cherries have not been bothered as much by the SWD. Maybe 5% of the fruit shows a brown spot similar to your first photo. The rest seem to be OK. Now that all of the sweet cherries are gone, the SWD may shift their attention to the sour cherries; so I plan to pick all of the sour cherries as quickly as possible. One useful characteristic of sour cherries is that they are better when picked slightly under-ripe; so I'll be doing that next year to minimize the damage. Unfortunately, sweet cherries keep getting better when they are over-ripe.

    With the cherries out of the way, the next thing to check is if the SWD are going to have an impact on other soft fruits in the garden. I grow practically every fruit mentioned as being on their menu.
     
  11. Natasha

    Natasha Member

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    Vitog, thank you so much for your reply. At least I have a handle on the problem. I am so sorry for the loss of your crop (as well as mine). As an organic gardener, how can one prevent the problem to reoccur next year?
    Thanks again for your interest.
     
  12. silver_creek

    silver_creek Active Member

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    One thing I learned at the SWD workshop I attended- freezing your fruit immediately upon picking will kill eggs/first instar larvae before they can ruin the fruit. That is one approach I'm taking with my berries- pick frequently and freeze or process immediately. The female lays the eggs in fruit just as it ripens; it takes a few days for the larvae to hatch and ruin the fruit. I also plan to put some of my chickens in the berry patch when I'm through harvesting to clean up any fallen fruit.

    There are few organic controls for SWD. One is a fruit fly bait that contains spinosad. I think it is available in Canada as well as the US as I've seen a Canadian label for it. CF 120 Naturalyte. This is sprayed at the first sign of SWD- the adults are attracted to it as a nectar source, and it kills them. Bad news- this seems to be the only organic control, and since they can have 8 generations a year, developing spinosad resistant population becomes a threat.

    Right now, I'm just using vinegar traps, trying to trap out adult populations (actually haven't confirmed SWD in my home garden, but it's well established where I work). And rapid harvest/processing of fruit. Because SWD will also go to salmon berry and wild blackberry, this pest is here to stay. Let's hope some natural predator is found to bring it into balance. Otherwise, I fear the home gardener who doesn't want to use petrochemicals will be battling this forever.
     
  13. K Baron

    K Baron Well-Known Member

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    A cool wet June can also be blamed, without spraying the tree, spring and fruit set periods, it may be that backyard fruit trees are the next target for pests... cherries are prone to the maggot fly and it is a pity that the only method known to be successful is chemical praying... But I think an organic solution is at hand.... any one care to add to this? Companion plantings, natural sprays, nettings????
     
  14. silver_creek

    silver_creek Active Member

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    Where I work, we have talked about next year using fine mosquito netting on the berries and even cherries. Most of our sweet cherries are grown in a high tunnel with a tarp cover, poly side walls and bird netting at the ends. We have had no SWD inside the tunnel. The other cherries had just a tarp cover with bird net sides- these became infested with SWD fairly early. We did use spinosad on those but we fear creating resistant populations, so are trying to figure out how to use mosquito netting instead of the bird netting to exclude the SWD next year. Although the farm is not organic, we try to be minimalists in use of chemical sprays. I think if heavy use of chemical sprays were necessary, we would stop growing cherries. :(
     

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