SWD Flights Continue to be Active in all Late-season Berry Crops

Authors: Bill Hutchison, Eric Burkness, Chulwoo Kim, Brianna Pomonis, Anh Tran, Dominique Ebbenga & Suzanne Wold-Burkness
MN Extension IPM Program, Dept. of Entomology, University of Minnesota, St. Paul campus

Spotted wing drosophila male (left), with characteristic spots on the wings, and female (right), with serrated ovipositor (egg-lay device). Photo:  Sheila Fitzpatrick, Agriculture & Agri-Food Canada, Pacific Agri-Food Research Center, Agassiz.

Spotted-wing Drosophila (SWD) trap catches continue to remain very high in all on-farm and research locations monitored. Traps in our network are effective at catching both male and female flies (Fig. 1).   Growers should remain diligent in alternating insecticides as much as possible (e.g., Delegate or Entrust [organic-certified], Mustang Maxx, and Malathion), and follow the pre-harvest and re-entry intervals, noted on the label for each insecticide. The most significant increase was Hastings this week, where wine grapes are now at véraison, with approx. 60% green berries. We will have more information next week regarding SWD management strategies for wine grapes. SWD numbers usually increase in wine grapes from late-August to mid-September, through harvest.

Table: Spotted-wing Drosophila (SWD) weekly trap catch updates, selected MN locations, Aug. 12th. Rosemount = fall raspberry; Forest Lake = summer raspberry; Hastings = wine grapes; HRC wine grapes + mixed; Houston Co. = mixed summer/fall raspberry.