The first sample of the year from a pre-harvest strawberry planting was negative for spotted wing drosophila (SWD). To date, we haven’t seen SWD in strawberries in Kentucky, but we have only 2 seasons of experience with SWD in our state. I still encourage producers to sample in their own fields for SWD beginning about 10 to 14 days before harvest. To date we have had SWD in cherries, blueberries, blackberries, raspberries, elderberries, and day-neutral strawberries in Kentucky. SWD activity has been too late to affect June bearing strawberries in previous years, but every producer knows that each year is unique. It is a significant pest of strawberries in southern and western regions of the country.
Trapping Spotted Wing Drosophila
The trap we are recommending is a clear 1 liter deli container with two 3-inch by 1.5-inch windows cut in the sides and pieces of 1/6-inch plastic screening glued in place over the windows. Each trap has about ½ cup apple cider vinegar plus one drop of dish soap as drowning solution. Hung on the inside from the lid is a commercial SWD lure to attract the flies. The lure only needs to be replaced monthly and used lures should not be disposed in the field.
Threshold for Spraying
Our threshold for spraying is 1 SWD. If SWD is not trapped, then sprays for SWD are not necessary. When SWD is captured, weekly sprays are recommended on susceptible crops every 7 days during the harvest period. See Spotted Wing Drosophila Management (ENTFACT 230) for management recommendations.
Trap Count Reports Around Kentucky
This summer, cooperators in about 22 Kentucky counties will be trapping for SWD in various small fruit crops. Results of the trapping will be posted weekly on the SWDinKY Facebook page.
By Ric Bessin, Extension Entomologist