Spotted Wing Drosophila Alert: 9/15/2022
David Handley, Vegetable and Small Fruit Specialist; James Dill, Pest Management Specialist, Phil Fanning, Assistant Professor of Agricultural Entomology, Christina Howard, New Farmers Program Manager
Spotted wing drosophila fly counts remain high this week, with trap counts roughly similar to last week, although lower in locations where the spray schedule was recently tightened. In the unsprayed site, numbers doubled this week, suggesting that fly populations are growing and the threat level to ripening fruit continues to be very high. Growers should maintain a tight, regular (5-7 day) spray schedule to prevent larvae from infesting fruit. It is likely, based on past years’ data, that fly numbers will continue to climb as long as food is readily available, and the weather conditions remain good for their development.
Growers should maintain a 5-7-day spray schedule on all soft-fruited crops, including fall raspberries, blackberries, and day-neutral strawberries to prevent infestation by spotted wing drosophila larvae. Sprays should continue as long as flies are present and there is still fruit to harvest.
Once harvest starts, it can be difficult to keep berry fields clean of over-ripe and rotten fruit, but field sanitation has been shown to significantly reduce drosophila numbers, so it pays to keep waste fruit off of the ground as much as possible to reduce food and egg-laying sites.
For more information on identifying spotted wing drosophila (SWD) and updates on populations around the state, visit our SWD blog at: https://extension.umaine.edu/highmoor/blog/tag/spotted-wing-drosophila/.
Other IPM Web Pages
Michigan State University: http://www.canr.msu.edu/ipm/invasive_species/spotted_wing_drosophila/
Penn State University: https://extension.psu.edu/spotted-wing-drosophila-part-1-overview-and-identification
David T. Handley
Vegetable and Small Fruit Specialist
Highmoor Farm Pest Management Office
P.O. Box 179 491 College Avenue
Monmouth, ME 04259 Orono, ME 04473
207.933.2100 1.800.287.0279
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Weekly spotted wing drosophila trap captures.
| Town | Spotted Wing Drosophila weekly trap catch 9/2/22 | Spotted Wing Drosophila weekly trap catch 9/9/22 | Spotted Wing Drosophila weekly trap catch 9/16/22 |
| Wells | 647 | 1184 | 270 |
| Limerick | 20 | 202 | 34 |
| New Gloucester | 166 | 577 | 331 |
| Bowdoinham | 47 | 86 | 224 |
| Mechanic Falls | 249 | 992 | 623 |
| Monmouth* | 1,519 | 1032 | 3,088 |
| Wayne | 799 | 832 | 622 |
*Unsprayed plot