Spring has arrived and several fruit crops are blooming or will soon bloom. The first of the spotted wing drosophila (SWD) susceptible crops will be strawberries, followed by cherries, blueberries, blackberries, fall raspberries, and grapes. SWD is a threat that requires monitoring and producers should be prepared to manage it as needed.
Trapping Spotted Wing Drosophila
In many parts of the country where markets have zero tolerance for SWD and other insects, producers spray their susceptible crops throughout the harvest period regardless of trap captures. Many Kentucky producers selling products locally do not have the strict zero tolerance and have used SWD trapping to identify if and when SWD sprays are needed. The result has been that we have not needed to control SWD in June bearing strawberries, and in some years, blueberries have escaped SWD activity. I recommend small fruit producers monitor SWD before and throughout the harvest period with adult traps.
The trap we are recommending is a clear 1 liter deli container, with two 3-inch by 1.5-inch windows cut in the side; plastic screening is glued in place over the openings. Each trap should have about ½ cup apple cider vinegar plus one drop of dish soap as a drowning solution. A commercial SWD lure to attract the flies is hung from the inside on the lid. The lure only needs to be replaced monthly, but used lures should not be disposed of in the field.
Our threshold for treatment is one trapped SWD on a farm. If SWD is not trapped, then sprays for SWD are not necessary; however, when SWD is captured, weekly sprays are recommended on susceptible crops for the remainder of the harvest period at weekly intervals. See Spotted Wing Drosophila Manatgement (ENTFACT-230) for management recommendations.
This year I am looking for cooperators in 20 to 30 Kentucky counties that would be willing to trap for SWD in their commercial small fruit crops. I can provide the trapping materials and plastic containers to mail the samples to me in Lexington. I will be reporting SWD activity with the participating counties on Facebook; results of the trapping will be posted on the SWDinKY Facebook site as samples are submitted
Ric Bessin, Extension Entomologist