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Fruit Growers Alert 8/9/13: Spotted Wing Drosophila Populations Jump in Coastal Site

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Fruit Growers alert – August 9, 2013

For full page print version, please see link at the bottom. Click on photos to enlarge.


Spotted wing drosophila (SWD) flies were captured in traps in Wells, Cape Elizabeth, Limington, New Gloucester, Gray, Monmouth, Bowdoinham and Corinna. Most traps had one to three flies in them, and there are still a few locations where we have not caught any flies. The exception was the Bowdoinham site, which had over 200 flies for the week. We had no data from our Dresden site, which is close by, this week (broken trap) but the count was higher there last week as well.

There have been more reports of maggots in blueberry fruit this week, but these are the larvae of was blueberry fruit fly (aka blueberry maggot), not spotted wing drosophila, as we reported last week. Blueberry maggot populations of this insect have been very high this season, and any plantings that were not sprayed as fruit began to ripen are susceptible to infestation. For a good fact sheet on this pest visit our web site. If you are finding larvae in harvested blueberry fruit, there is a fact sheet from North Carolina State University website to help identify which insect is causing the problem.

Spotted Wing Drosophila Larva in Blackberry

SWD Larvae in Blackberry, photo by David Handley

Spotted Wing Drosophila Maggot in Raspberry

SWD Larva in Raspberry, photo by David Handley

There is no valid threshold for spotted wing drosophila in berry fields. If SWD has been captured in your area and you have ripe or nearly ripe fruit in your fields, the crop should be protected with a recommended insecticide. Products that provide good control of drosophila on berries include Delegate®, Brigade®, Bifenture®, Danitol®, Mustang Max®, malathion and Assail®. Effectiveness of these products can range from three to seven days. Repeated applications throughout the harvest season may be required to prevent larvae from infesting the fruit. Please check product labels for rates, post-harvest intervals and safety precautions. Keeping the fields clean of over-ripe and rotten fruit can also help reduce the incidence of this insect.

David T. Handley
Vegetable & 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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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.

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