SWD Update 21 June 2012

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Spotted Wing Drosophila Update
By the SWD Team

June 21, 2012

Blueberry and Caneberry in Western Oregon

This will be the third growing season managing spotted wing drosophila (SWD), Drosophila suzukii, in Oregon small fruit and each year is different.  We observed no problems with SWD the first year, 2010, probably because Oregon growers did not risk their crop and sprayed specifically for SWD.  Last year, 2011, SWD was almost a no-show probably because of several cold snaps.  This year, 2012, appears to be different from the previous two years because we are capturing more flies earlier and in more locations than in 2010 and 2011.  This fact is being observed throughout the Pacific Northwest.  We suspect the milder winter allowed more flies to successfully overwinter. 

It appears that apple cider vinegar traps are not that effective in capturing flies from more than short distances.  Relying on SWD counts from one or two traps may not be prudent.  Place more traps, especially in hot-spot areas of your property and pay attention to the weekly SWD reporting put together by Wei Yang and Tom Peerbolt (spottedwing.com).

Research has indicated that protecting fruit from first color through harvest is critical and that the last 2-3 sprays before harvest are the most important.  Research has demonstrated that the most effective SWD materials are OPs (diazinon, Imidan, and malathion), synthetic pyrethroids (Asana, Brigade, Danitol, and Mustang Max) and spinosad/spinetoram (Success-Entrust/Delegate).  OPs and pyrethroids kill SWD faster than does Success, Entrust or Delegate.  Carbamates (Sevin and Lannate) are also effective materials.  Research has demonstrated that neonicotinoids (Actara, Assail, and Provado) are not as effective as the OPs, synthetic pyrethroids, or carbamates against SWD.New lab studies are showing that female SWD treated with Pyganic (a pyrethrin product) can recover from an application and lay fertile eggs. Check pesticide tables to design a prudent control program (Insert link here) and be cognizant of Maximum Residue Levels (MRLs) if exporting to foreign markets. 

If your fruit is beginning to show color, use effective SWD control materials.  It is important to "zero-out" any flies that may be in your field using an application of an effective SWD material by ground when you target your first spray for SWD.  Malathion ULV by air has been shown to be effective in cherries and may be an option for blueberries as a substitute for the first SWD spray.

Late harvested crops and cultivars are probably more at risk for SWD damage compared to early harvested crops because SWD populations will be greater later in the season.  Be sure to protect your crop with effective insecticides against SWD.   Contact your extension agent or crop consultant regarding the most effective control for SWD in this critical period.

SWD control

Monitoring: Begin immediately prior to blush of color through harvest. Place apple cider vinegar (ACV) traps, concentrating on field margins, inside rows to provide some shade. Replace ACV bait weekly and check for SWD presence. For detailed monitoring information, visit spottedwing.com.
Control: Currently, SWD control relies primarily on insecticides.  Please consult the PNW pest management handbook for more details regarding control of SWD.



Editor: Wei Yang

Contributing authors: Amy Dreves, Denny Bruck, Jana Lee, Joe DeFrancesco, Vaughn Walton