Spotted Wing Drosophila Update – August 12, 2022
Spotted Wing Drosophila Alert: 8/12/2022
David Handley, Vegetable and Small Fruit Specialist; James Dill, Pest Management Specialist, Phil Fanning, Assistant Professor of Agricultural Entomology
Fly counts rose significantly at most, but not all, locations this week, perhaps signaling the start of the expected exponential growth of fly numbers we typically see at this point in the season. Sites over the six-fly threshold that is considered potentially damaging to ripening berry crops included Wells, Limerick, New Gloucester, Bowdoinham, Monmouth, and Wayne. Growers should expect larvae to start appearing in the fruit unless protective sprays are applied (see table below).
Spotted wing drosophila build rapidly, and with trap counts showing a 3 to 10-fold increase this week, populations are expected to continue to rise. Protective sprays should be applied on any ripening fruit, and growers should maintain a 5-7-day spray schedule once fly numbers have exceeded the threshold or larvae are noticed in the fruit. Look for fruit flies hovering around fruit and symptoms of premature fruit decay.
Keep berry fields clean of over-ripe and rotten fruit as much as possible. Rotten fruit on the plants or on the ground will greatly increase the number of fruit flies present, by providing them with 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
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