Spotted Wing Drosophila Alert: July 27, 2018

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

We continue to capture spotted wing drosophila fruit flies in vinegar/yeast traps in raspberry and highbush blueberry plantings this week, but mostly in low numbers. (See table below.) While these counts may indicate that populations are still fairly low in berry fields, growers who have been catching flies in their traps for more than one week and have ripening fruit should put on a protectant spray. We have had reports of raspberry fruit infested with larvae from an unsprayed field.

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Spotted wing drosophila populations are expected to rise in the coming weeks as more ripe fruit becomes available for the flies, especially if conditions remain warm and wet. Set out traps now, if you haven’t already. Start protective sprays on any berries that have begun to ripen when: more than four spotted wing drosophila flies are caught in a trap, flies are caught consistently for more than one week, or any larvae are noticed in the fruit. Look for fruit flies hovering around fruit and symptoms of premature fruit decay.

Remember to keep waste fruit out of the field as much as possible. Harvest often and regularly to prevent the presence of overripe fruit; and open up the planting to more light by pruning out excess vegetative growth, especially in the lower part of the bush canopy.

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

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
Sanford 13 3
Limington 1 1
Limerick 0 0
Buxton 3 5
Bowdoinham 1 1
Dresden 5 2
Freeport 0 0
Poland Spring 1 0
Mechanic Falls 0 0
Monmouth 3 0
Readfield 0 1
Wales 5
Farmington 8
Fayette 0 0
Wayne 0