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Spotted Wing Drosophila Monitoring Update

Posted: June 27, 2014

With the cold winter last season, we are expecting a higher than normal winter mortality, and hopefully a later than usual emergence of spotted wing drosophila. At this time, we do not believe cherries are at risk and that we probably have at least another week before the first flies will be caught.

Since its initial discovery in a Pennsylvania cherry orchard in 2011, Spotted Wing Drosophila (SWD) has quickly spread throughout most of the state and populations have increased.

Monitoring Strategies

Monitoring with clear plastic traps baited with apple cider vinegar (ACV) alone or with ACV and red wine gave us first detections of low levels of this pest as tart cherry harvest was completing – or around July 10. Fruit surveys from last season from many different small fruit and tree fruit crops at over 100 locations found that strawberries were not at risk from SWD nor were cherries picked at normal timing, but late harvested cherries in a U-Pick operation did have larvae in the fruit.

With the cold winter last season, we are expecting a higher than normal winter mortality, and hopefully a later than usual emergence of SWD.  To aid us and growers in monitoring SWD, Trece has developed a much improved 2-part lure that is just as effective as the yeast baits, but not nearly as messy or nasty smelling.  Much more effective than the ACV bait alone, we are testing it suspended over ACV as the killing and preserving fluid at about 60 locations in Pennsylvania and Maryland this season.  The lure which is supposed to last for 4 weeks is also better at attracting female flies earlier in the season than ACV alone and should give us more lead time in timing sprays.  We purchased our Trece SWD Dry Lures from Great Lakes IPM in Vestaburg, MI and our first samples, placed a week ago and evaluated today, still have not produced SWD flies of either sex.  We will continue to monitor our traps all season and report our catches in real time to better inform growers when to spray.

Likely another week before first flies will be caught

Trapping with these commercial lures and using commercial or home-made deli cup traps will of course give you better information on the abundance and timing of SWD on your own farm.  At this time, we do not believe cherries are at risk and that we probably have at least another week before the first flies will be caught.  This would put blueberries and black raspberries as the first crops historically at risk, but with the high winter mortality, we should be able to tell you if sprays for these crops will be needed.  Traditionally blackberries and late season raspberries have been the favorite crop and growers would be advised to run their own traps or to keep following our trapping numbers for timing sprays and recommendations on which insecticides to use.

Cooperative effort with Bryan  Butler, University of Maryland Extension

 

Contact Information

Dave Biddinger
  • Tree Fruit Research Entomologist
Phone: 717-677-6116
Kathy Demchak
  • Senior Extension Associate
Email:
Phone: 814-863-2303