Spotted Wing Drosophila Alert: August 3, 2017

Spotted Wing Drosophila Trap Catch
Spotted Wing Drosophila Trap Catch; photo by Christina Hillier

Click on photos to enlarge.

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

Spotted wing drosophila activity continues to increase at most trapping sites this week. (See table below.) Most of the trap counts are above what we consider potentially damaging to ripening berry crops, especially raspberries, blackberries and blueberries. Research suggests that when 6 to 10 flies are caught in a yeast-baited trap in a week, larvae will start appearing in the fruit. At this point, a spray schedule of 7 to 10 days apart should be adequate to prevent fruit infestation at most locations. However, at sites where higher populations are now occurring (New Gloucester, Farmington, Limerick, Bowdoinham), fruit may need to be under a five to seven-day spray interval to achieve adequate protection.

Spotted Wing Drosophila on Raspberry
SWD on Raspberry; photo by David Handley.

Spotted wing drosophila (SWD) populations are likely to continue rising in the coming weeks. Look for fruit flies hovering around fruit and symptoms of premature fruit decay. Remember, the flies favor shady, moist regions of the planting. Flies can be discouraged by harvesting regularly to prevent the buildup of overripe fruit, removing all rotten or cull fruit from the field, and pruning out excessive vegetative growth that provides shade and cover for the flies.

Other IPM Web Pages

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm, P.O. Box 179, 52 US Route 202, Monmouth, ME 04259, 207.933.2100

UMaine Extension Diagnostic Research Lab, Pest Management Unit, 17 Godfrey Drive, Orono, ME 04473, 1.800.287.0279

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Town Spotted Wing Drosophila weekly trap catch
Spotted Wing Drosophila weekly trap catch
Spotted Wing Drosophila weekly trap catch
Wells 8 12 12
Sanford 6 16 8
Limington 7 21 233
Limerick 4 18 19
Cape Elizabeth 37 68 65
Buxton 3 5 14
New Gloucester 298 600 780
Bowdoinham 28 74 128
Dresden 2 13 47
Freeport 4 10 3
Poland Spring 2 4 22
Mechanic Falls 0 0
Monmouth 5 1 2
Wales 121 78 85
Farmington 9 141 123
Fayette 5 7 8