Spotted Wing Drosophila Alert: September 29, 2017
David Handley, Vegetable and Small Fruit Specialist; James Dill, Pest Management Specialist; Frank Drummond, Professor of Insect Ecology/Entomology
Spotted wing drosophila numbers were variable from site to site this week, with some locations seeing little change or a slight decrease from last week, while others showed a significant increase. This may be due to the availability of fruit at each site, as the season starts to wind down, spraying at a site, or trap exposure during the recent hot, sunny days. It is important to note, however, that all locations still have drosophila numbers high enough to cause significant damage to any ripening fruit remaining in the fields. (See table below.) Fall raspberries and day-neutral strawberries are very susceptible at this time. We have also had reports of peaches being infested over the past week. Typically, thicker-skinned fruit like peaches, plums and grapes are not very susceptible to spotted wing drosophila unless the skin is cracked or wounded, which provides the flies with easy access to the flesh for egg laying. It is important to keep wounded and rotten fruit out of the field as much as possible. Allowing it to stay on the plant or on the ground will attract more flies and provide food and shelter for more eggs and larvae.
Growers with any ripening fruit should continue protecting their crop against egg-laying drosophila. A minimum spray interval of 5 to 7 days is recommended to keep fruit from becoming infested.
For more information on identifying spotted wing drosophila and updates on populations around the state, visit our SWD blog.
David T. Handley
Vegetable and Small Fruit Specialist
Highmoor Farm, P.O. Box 179, 52 US Route 202, Monmouth, ME 04259, 207.933.2100
UMaine Extension Diagnostic Research Lab, Pest Management Unit, 17 Godfrey Drive, Orono, ME 04473, 1.800.287.0279
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