SPOTTED WING DROSOPHILA UPDATE: August 7, 2020
SPOTTED WING DROSOPHILA UPDATE: August 7, 2020
David Handley, Vegetable and Small Fruit Specialist; James Dill, Pest Management Specialist, Christina Howard, Produce Safety Professional
Click on photos to enlarge
Spotted wing drosophila (SWD) fruit fly numbers increased at nearly all of our monitoring sites this week, and we should expect higher numbers next week because the recent tropical storm probably brought up more flies from southern regions. Trap counts are well above levels considered damaging to ripening berry crops, especially raspberries and blueberries. Fall crops of day-neutral strawberries are also susceptible (see table below). Sites capturing more than four SWD flies in a week should remain on a protective spray schedule to prevent fruit from becoming infested with larvae. A seven-day spray interval may still be adequate at most sites, but it is likely that a five day interval may become necessary soon, given the higher populations now present.
Remember that keeping the field free of waste fruit can significantly reduce drosophila numbers. All fruit should be chilled to 34 degrees F (or as close as possible) immediately after harvest to halt development of any eggs or larvae. If larvae are noticed in the fruit despite a 7-day spray schedule, a 5 day spray schedule is recommended. Look for fruit flies hovering around fruit and symptoms of premature fruit decay. The flies are most prevalent in the lower, shaded parts of the plants.
Be sure to read and follow all pesticide product labels carefully, especially in regards to days to harvest restrictions and the number of applications allowed per growing season. Rotate products used regularly to prevent the possible development of resistance. Current information on registered pesticides for managing SWD is available in the New England Small Fruit Management Guide. The online version is free and can be viewed here
For more information on identifying spotted wing drosophila (SWD) and updates on populations around the state, visit our blog
Other IPM Web Pages
Michigan State University
David T. Handley
Vegetable and Small Fruit Specialist
Highmoor Farm Pest Management Unit
P.O. Box 179 17 Godfrey Drive
Monmouth, ME 04259 Orono, ME 04473
207.933.2100 1.800.287.0279
Where brand names or company names are used it is for the reader’s information. No endorsement is implied nor is any discrimination intended against other products with similar ingredients. Always consult product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.
The University of Maine is an equal opportunity/affirmative action institution.
| Town | Spotted Wing Drosophila weekly trap catch 7/24/20 | Spotted Wing Drosophila weekly trap catch 7/31/20 | Spotted Wing Drosophila weekly trap catch 8/7/20 |
|---|---|---|---|
| Wells | 21 | 3 | 4 |
| Sanford | 2 | 40 | 135 |
| Limington | 8 | 115 | 893 |
| Limerick | 24 | 21 | |
| Cape Elizabeth | 1 | 121 | 31 |
| Bowdoinham | 371 | 750 | 1021 |
| Mechanic Falls | 0 | 0 | 11 |
| Monmouth | 15 | 100 | 61 |
| Wayne | 13 | 36 | 661 |