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Fruit Growers Alert 8/16/13: Spotted Wing Drosophila Spreading, Counts Increasing

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Fruit Growers Alert – August 16, 2013

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Spotted Wing Drosophila Trap

SWD Trap, photo by David Handley

Spotted wing drosophila (SWD) flies were captured in traps in Bowdoinham, Cape Elizabeth, Dresden, Gray, Limington, Livermore Falls, Mechanic Falls, Monmouth, New Gloucester, Springvale, Wales, Warren and Wells.  Trap captures varied this week from just one fly to over 100, with most catching fewer than 10.  There are now just a few sites where we haven’t yet caught any flies.   The Bowdoinham site again had far more flies than any other location (135) although this was only about ½ the number we caught at the same location last week. The other sites with higher numbers were Wells (21) and Wales (18).  Some of this variation may just be a matter of where the traps are placed at each site.  Ideally, growers should set up their own traps to monitor for SWD, and learn to distinguish it from other species that will get into the trap.

Male and Female Spotted Wing Drosophila

Male and Female Spotted Wing Drosophila, image by Alan Kenage, Capital Press

While there is no valid threshold for spotted wing drosophila in berry fields (most buyers have zero tolerance), growers should initiate a regular insecticide spray program once SWD is captured in your area and you have ripe or nearly ripe fruit in your fields. 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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