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Questions about SWD

Posted by NilaJones 7b (My Page) on
Fri, Aug 16, 13 at 13:03

I have spotted wing drosophila in my blackberries :(.

I have read several of the threads on the topic here -- horribly sad stories of people ripping out their orchards -- and some of the extension websites (Davis, OSU, etc.). I have a few questions that I am hoping you folks will have answers to.

- Do the flies only go for fresh fruit, or also for composting? I froze a lot of peaches yesterday, and put the peels in my compost pile. Then I wondered if I should not have done that. Should I not put any fruit stuff in the compost, and pick out what is there?

- Has anyone found a cheap source for large quantities of netting? I'd love to find something about 20 feet wide, or more, and about 50 feet long.

- I got friends to help me pick up every dropped blackberry, and everything black in color off the bushes, and put in ziploc bags in the trash. Was this the right thing to do? Luckily I got 2/3 of my crop before the flies moved in.

- Are my grapes safe if the fruit is undamaged? I have a huge crop, and normally leave them on the vine until December, because they keep that long if unpicked. Do I need to do something different this year?

My head is swimming with the magnitude of this problem. I am grateful for any advice.


Follow-Up Postings:

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RE: Questions about SWD

http://utahpests.usu.edu/ipm/htm/fruits/fruit-insect-disease/spotted-wing-drosophila

Here is a link that might be useful: covers


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RE: Questions about SWD

Thanks for the links, gator :).

Looks like I should get all fruit out of my compost pile.

I have used the floating row covers you linked to (for other stuff). I am looking now for a larger quantity at lower cost.


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RE: Questions about SWD

  • Posted by lkz5ia z5 west iowa (My Page) on
    Fri, Aug 16, 13 at 19:23

well you aren't alone, about most of america has it in some degree, don't notice it until it hits the cloud stage. I wouldn't doubt if there is a million on this place, no stopping it, just take satisfaction in eating fruit fly eggs while my hens are not laying, haha what a sad joke


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RE: Questions about SWD

I've always kept fruit out of the compost. Besides the SWD, it attracts wasps, sap beetles and other pests.


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RE: Questions about SWD

Bagging and trashing the fruit was the right thing to do.

Setting out early vinegar traps is best for early detection well before cloud stage.


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RE: Questions about SWD

I have not seen any clouds, thank goodness. But plenty of maggots.

Here are a couple links from discussions in the vegie forum about sourcing bulk fabric, for those who are interested:

http://forums.gardenweb.com/forums/load/cornucop/msg0422501923825.html

If you scroll down in this one, one poster has thoughtfully provided pics, and another numbers, so that we can know the sizes of holes in various kinds of mesh:

http://forums2.gardenweb.com/forums/load/cornucop/msg0505305828412.html

GW sure does rock :).

After some time getting used to the idea, I think netting my berries next year might not be all that impossible.

I can lay the net on the trellis before I tie up the new stalks in the winter, and leave the other side open for pollination. (Dunno if I am explaining this clearly.) The rest, that grow in heaps, I can cover.

I may sew lengths of fabric together to make wide swaths. Unless someone finds a better source!

But how do you seal the netting around the stems at the bottom of the plants? Lay it on the ground and weigh it down with mulch?


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RE: Questions about SWD

Before I reinvent the wheel, have any of you folks looked into light transmittance, in the wavelengths plants use, of different colors of fabric?

People on those vegie threads talk about using green for looks, but one of my blackberry patches has limited sun, as do the raspberries, and I don't want to further reduce it more than I have to. Am wondering if a lighter color makes a difference.

I live in the PNW, where gardeners have to distinguish between minute gradations of light -- not just full sun and partial shade!


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RE: Questions about SWD

Nila,
My buffalo, canadice grapes were untouched with surround this year, while last year they were shot. So were the black berries. _This year, my later blackberries are really affected.
I think it's a nightmare.


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RE: Questions about SWD

Blackberries are self-pollinating, so covering during flowering is fine, but it would deprive the bees during a period when the SWD is not active.

If you are considering the tulle stuff, I'm not sure the mesh is fine enough. All the light-colored row covers and tulle let in plenty of light for the ripening and proper greening of foliage, even in the PNW; in fact, blackberries may benefit from some shading during the harvest season.

Whatever system you come up with should have as the top priority: How will the cover be removed for berry picking every three days, and then re-sealed.


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RE: Questions about SWD

@larry-gene:

>Whatever system you come up with should have as the top priority: How will the cover be removed for berry picking every three days, and then re-sealed.

Thank you! That is an excellent point!

>If you are considering the tulle stuff, I'm not sure the mesh is fine enough.

Did you look at the pics and stats in the other thread? How small do you think is needed? Not sure if row cover is small enough, either :(.

>All the light-colored row covers and tulle let in plenty of light for the ripening and proper greening of foliage, even in the PNW; in fact, blackberries may benefit from some shading during the harvest season.

The berries I am concerned about are already pushing their limits as far as the amount of shade they are in. The other varieties, in full sun, I agree will be happy with the covering. Do you think it will be the last straw?

@Noogy:

>My buffalo, canadice grapes were untouched with surround this year, while last year they were shot. So were the black berries. _This year, my later blackberries are really affected.
I think it's a nightmare.

So sorry about your crops :(.

Do you mean 'surround' the pesticide, or do you mean fabric? Did you use one or both on your grapes?

I see from online stuff that SWD seem to like grapes in the eastern US but not in the west -- but there is speculation this has to do with climate, and mine are mostly in a greenhouse.


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RE: Questions about SWD

The whitish row covers would be plenty fine-meshed, as would mosquito netting material--the SWD is stockier than a mosquito, but is a little smaller overall.

I think your shady berries will be fine; there is a row of wild berries not far from here that are north-facing and backed by buildings and large trees and they ripen late but do well.
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SWD males go sterile in temperatures above 86 degrees, so climate is a factor in how their populations swell in any one locale. A greenhouse allowed to get repeatedly warmer than this might control the SWD.


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RE: Questions about SWD

@larry_gene:

>SWD males go sterile in temperatures above 86 degrees, so climate is a factor in how their populations swell in any one locale. A greenhouse allowed to get repeatedly warmer than this might control the SWD.

Oh, thank you, this is very helpful! As is all of your post :))).

I don't think the grapes will mind it hot :).

@Noogy: Oh, I see I misremembered -- Surround is not a pesticide exactly, but is kaolin clay. Is that what you meant?


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RE: Questions about SWD

Most of the nation was above 86 degrees the past two summers. Who came up with that figure?
Northwoodswis


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RE: Questions about SWD

Insect pests with economic impacts are studied thoroughly:

http://www.ipm.ucdavis.edu/EXOTIC/drosophila.html

contains the temperature info.


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