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Spotted Wing Drosophila

Posted by Doug Newman 
Spotted Wing Drosophila
February 02, 2013 02:03AM
To organic growers: is SWD proving to be a serious problem in your area and if so, how are you dealing with it? Have you had fewer problems with earlier bearing varieties?

Doug Newman
Buried Treasures Organic Farm
Groton, New York
Zone 5b

Re: Spotted Wing Drosophila
February 13, 2013 11:52PM
Everyone should be prepared for this pest in North America. Here in northernmost Vermont we thought we would skirt it, but to no avail. Our blueberry cultivars and most other fruits escaped it, but later maturing crops took a hit. Grapes, even those in greenhouses were attacked. Other farms in the area were hit very hard, especially fall raspberries and late blueberries. Reams will be written on this subject here I am sure, as it is the new scourge. It isn't a major concern for processed fruits, but fresh fruit can see the maggots so plentiful within berries to see fruit actually wiggle. Even for the unsqueemish, that is gross.
Re: Spotted Wing Drosophila
February 14, 2013 04:23AM
This came in tonight, part of a summary of research presentations made at the recent Great Lakes Fruit & Vegetable Expo:

Rufus Isaacs, the Michigan State University (MSU) berry crops entomologist, provided an overview of organic SWD management. At present this insect threatens growers of raspberries, blueberries, cherries, strawberries and peaches. Growers are advised to maintain a rigorous detection program and begin treating crops with Entrust® once adult flies are detected. Pyganic® may also provide limited control and can be rotated with Entrust® applications. Regular harvest intervals and removal of ripe fruit from the planting floors also appears to help with SWD management. Refrigerating fruit immediately after harvesting may also help by slowing SWD larval development. Alternative management options are being researched with exclusion using netting or high tunnels high on the list of possible solutions. Long-term mitigation of this pest will likely depend on biological control but our native parasitoids do not seem capable of overcoming SWD’s immune response. Growers with soft fruit crops that mature after July should be especially vigilant in monitoring and managing this pest.
Re: Spotted Wing Drosophila
February 14, 2013 08:11PM
And today's phone call with orchard buddy Maury Wills in Iowa helped point to a far better response:

Meet Bob Wilt, an organic blueberry grower outside of Corvallis, Oregon. Bob's emphasis is on growing nutrient dense berries. This means applying foliar sprays of sea minerals and liquid fish and compost tea, allowing taprooted weeds to remineralize the soil, and investing in making plenty of good compost. You can watch a series of videos on his Sunset Valley Organics website. The relevance comes as a verbal affirmation given in a phone call: Neighboring berry growers are dealing with significant SWD pressure. His blueberries typically acheive a Brix reading of 20. Spotted wing drosophila are a non-issue at Sunset Valley.

We use spray medicines of whatever persuasion to make up for biological and nutritonal deficiencies. Any pest scourge is not going to be drawn to a healthy plant, period. I'm excited about upping the nutritional ante in my berry plantings (and everywhere else) even more this season.

Edited 1 time(s). Last edit at 02/15/2013 01:29AM by Michael Phillips.
Re: Spotted Wing Drosophila
March 27, 2013 07:51PM
Here's a simple method from trap/bait construction. Appears that the black line is very important in helping SWD "find its way." Also recently heard the first SWD of the seasonw as caught somewhere in Massachusetts (not sure where) along a wooded edge, suggesting that this is where they overwinter. So, if they've seemingly survived this past winter in woods, expect a rather robust SWD season.

12 fl oz water, four T sugar, 1 T active dry yeast, 1 T apple cider vinegar, 1-2 T whole wheat flour.

Suggest a red Solo cup with lid, and that a black stripe around the cup where the entrance holes are punched would increase attractiveness.

Testing Assail this summer with sugar added as a feeding stimulant to improve control.

It looks to me like about the width of a sweet cherry, or conveniently about the width of black electrical tape. You can just make out the presence of holes in the black stripe.

I think that the best entry would be a window cut in a red cup, to which a screen large enough to allow SWD entry, but small enough to exclude larger flies. Otherwise, use lots of holes of only about 2 mm diameter. A soldering iron may be O.K. for making these holes.

Mike Biltonen, Know Your Roots
Zone 5b in New York
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