Spotted Wing Drosophila Alert — September 12, 2025
David Handley, Vegetable and Small Fruit Specialist; James Dill, Pest Management Specialist, Phil Fanning, Assistant Professor of Agricultural Entomology, Christina Howard, Maine New Farmers Project Manager
Spotted wing drosophila fruit fly trap counts remain fairly stable and moderate at this time. Sites that are no longer spraying because harvest is complete are seeing higher numbers than sites that are still harvesting and spraying to protect the remaining crop (see table below). As colder temperatures set in, we expect a slowdown in activity, but flies can remain active even after the first few fall frosts. Should we see any tropical weather activity move in from the south in the coming weeks, drosophila activity could increase significantly and suddenly. Growers with late raspberries, blueberries and day neutral strawberries should continue to monitor their plantings closely for flies and regularly check fruit for larvae. A 5 to 7-day spray schedule on ripening fruit may be required to keep it in good, marketable condition.
If you are growing raspberries, blackberries and/or blueberries, you should be managing spotted wing drosophila on any fruit that is presently ripening and/or being harvested to prevent infestation.
For more information on identifying spotted wing drosophila (SWD) and updates on populations around the state, visit our SWD blog.
It’s Soil Testing Time: Early fall is a good time to seed cover crops, and is also a great time to take soil samples. Getting your soil tests results before the ground freezes allows time to correct soil pH with additions of lime, and to incorporate any needed nutrients into the soil, such as phosphorus, potassium, or magnesium, and to apply manure to increase organic matter. Fall applications of lime and nutrients (not nitrogen, as it is prone to leaching) are often ideal, because the fields are drier than in the spring, making applications easier, and nutrients will have time to reach the root zone before the plants need them. You can pick up soil test boxes and forms at any county office of the University of Maine Cooperative Extension, or call us here at Highmoor Farm if you’d like us to send you some. For details on soil testing, visit the University of Maine Analytical Laboratory and Soil Testing Service website.
Vegetable & Berry Growers Twilight Meeting: Friday, October 3, 5:00 p.m. at Bell Farm in Auburn, ME.
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
David T. Handley
Vegetable and Small Fruit Specialist
Highmoor Farm
P.O. Box 179
Monmouth, ME 04259
207.933.2100
UMaine Extension Diagnostic Research Lab
Pest Management Unit
17 Godfrey Drive
Orono, ME 04473
1.800.287.0279
| Town | SWD weekly trap catch 8/15/25 | SWD weekly trap catch 8/22/25 | SWD weekly trap catch 8/29/25 | SWD weekly trap catch 9/5/25 | SWD weekly trap catch 9/12/25 |
|---|---|---|---|---|---|
| Wells | 135 | 323 | 468 | 341 | 222 |
| New Gloucester | 190 | 57 | 128 | 69 | 141 |
| Cape Elizabeth | 474 | 388 | 695 | 798 | 293 |
| Bowdoinham | 27 | 103 | 139 | 141 | 60 |
| Mechanic Falls | 86 | 115 | 220 | 71 | 71 |
| Monmouth | 40 | 24 | 30 | 13 | 11 |
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