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Fruit Growers Alert 9/30/13: Spotted Wing Drosophila Counts Remain at High Levels

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Fruit Growers Alert – September 30, 2013

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


We continue to capture spotted wing drosophila flies at all of our monitoring sites from southern, mid-state and coastal Maine. While counts have dropped in some locations over the past week, levels are still high enough to infest any unprotected berries still remaining in the field. Highest counts have been at the coastal sites and lowest counts have been in the more northern and western sites. Our experience has shown that the flies will survive through repeated frosts and continue to infest fruit well into the fall. Therefore, any farms that still have late ripening raspberries, blackberries, blueberries, grapes or day neutral strawberries should continue to protect their crops with an approved insecticide. In some locations a 7-day spray interval may be adequate to prevent infestation, but areas with high fly populations may still require a 4 to 5-day spray schedule.

Spotted Wing Drosophila Larva in Blackberry

SWD Larvae in Blackberry, photo by David Handley

Spotted Wing Drosophila Maggot in Raspberry

SWD Maggot in Raspberry, photo by David Handley

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.  Please check product labels for rates, post-harvest intervals and safety precautions.

Four Rules for Managing Spotted Wing Drosophila:

  1. Spray ripening fruit regularly with an approved insecticide (every 5-7 days).
  2. Harvest crop frequently and regularly; remove all ripe and rotten fruit from the field.
  3. Chill all harvested fruit immediately to as close to 33º F as soon as possible; hold in refrigeration until ready to sell.
  4. Open up the planting through pruning and spacing to improve light and air penetration and reduce moisture and humidity within the plant canopy.

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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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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