Spotted Wing Drosophila Alert and Berry Notes — September 1, 2023

David Handley, Vegetable and Small Fruit Specialist; James Dill, Pest Management Specialist, Phil Fanning, Assistant Professor of Agricultural Entomology, Christina Howard, Maine New Farmer Project Manager

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

Spotted Wing Drosophila:

Populations of spotted wing drosophila remained relatively steady this week, with captures higher in some fields, lower in other fields, but no major changes, except where spraying schedules have been altered. Numbers are high enough to pose a significant threat to any ripe or ripening berries remaining in the field, so growers should maintain a regular, frequent spray interval to prevent larvae from infesting their fruit. We expect populations to remain high or escalate in the coming weeks, as the weather forecast calls for relatively warm conditions with the possibility of southern storm fronts moving into the northeast, which may carry more fruit flies into the state. In the past we have not seen populations significantly decline until we have experienced several hard frosts, and/or food supplies have been depleted.

At this point, a 5-7 day schedule of sprays may be needed to minimize fruit infestation in fields.

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

Other IPM Web Pages
Michigan State University Spotted Wing Drosophila
Penn State University Spotted Wing Drosophila Overview
University of New Hampshire SWD Weekly IPM Reports

raspberries ripening on the cane
Raspberries at Highmoor Farm; photo by Peyton Ginakes

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm
P.O. Box 179
Monmouth, ME 04259

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

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Weekly Spotted Wing Drosophila Trap Captures

Town Spotted Wing Drosophila weekly trap catch 8/4/23 Spotted Wing Drosophila weekly trap catch 8/11/23 Spotted Wing Drosophila trap catch average for 8/14/23 – 8/25/2023 Spotted Wing Drosophila weekly trap catch 9/1/23
Wells 22 166 600 276
Limington 2 19 104 65
New Gloucester 214 280 840 400
Mechanic Falls 20 34 976 1,029
Bowdoinham 42 138 624 158
Monmouth (unsprayed plot) 43 114 1,408 168
Wayne 8 1,012 1,012