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Spotted Wing Drosophila Alert: August 17, 2018

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David Handley, Vegetable and Small Fruit Specialist; James Dill, Pest Management Specialist; Frank Drummond, Professor of Insect Ecology/Entomology

Captures of spotted wing drosophila (SWD) fruit flies in vinegar/yeast traps in raspberry and highbush blueberry plantings increased significantly at some locations this week, and is above threshold levels at most sites. Our highest counts of the season were found in raspberry plantings in Wales and Cape Elizabeth, with numbers now reaching into the thousands. (See table below.) Weather predictions suggest that conditions will continue to be good for SWD to continue increasing in fall raspberries, late blueberries, elderberries and fall strawberries. Growers with these crops should be putting on regular protective sprays if more than 4 flies have been captured in traps in a week. At this point a 5 to 7-day spray schedule should be adequate for most plantings. Make sure your sprayer is providing good coverage of the plant surface, especially in the lower part of the canopy.

Spotted Wing Drosophila Larvae in Elderberries

Spotted Wing Drosophila Larvae in Elderberries, photo by David Handley

For more information on identifying spotted wing drosophila and updates on populations around the state, visit our SWD blog.

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Michigan State University
Penn State University
University of New Hampshire

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                      UMaine Extension Diagnostic Research Lab
P.O. Box 179                             Pest Management Unit
52 US Route 202                     17 Godfrey Drive
Monmouth, ME 04259          Orono, ME 04473
207.933.2100                           1.800.287.0279

Where brand names or company names are used it is for the reader’s information. No endorsement is implied nor is any discrimination intended against other products with similar ingredients. Always consult product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.

The University of Maine is an equal opportunity/affirmative action institution.


Town Spotted Wing  Drosophila weekly trap catch 8/3/18 Spotted Wing  Drosophila weekly trap catch 8/10/18 Spotted Wing  Drosophila weekly trap catch 8/17/18
Wells 0 0 5
Sanford 0 5 7
Limington 12 Trap down 23
Limerick 0 7 1
Buxton 0 11 58
Bowdoinham 2 34 152
Cape Elizabeth 1 18 1441
Dresden 5 49 10
Freeport 0 2 7
Poland Spring 0 2 7
Mechanic Falls 0 2 2
Monmouth 2 20 74
Readfield 12 17 51
Wales 2 216 4616
Farmington 1 0 3
Fayette 0 1 0
Wayne 0 0 1



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