SWD update June 16: Spotted wing drosophila adults are active already. We have found low numbers of flies at sites in Essex, Norfolk Oxford, and Halton counties and Niagara and Durham region. This is about three weeks earlier than normal.
Degree day models for southern Ontario suggest that the overwintering generation of SWD is laying eggs in fruit. In earliest areas, the model predicts that the first generation of flies is beginning to emerge from infested fruit. Since the only fruit present right now is strawberries and haskaps, these crops are theoretically at risk. We do not normally see damage on strawberries and haskaps until after the June harvest is over, so I am reluctant to suggest special sprays for SWD at this time. However, watch closely for signs of premature breakdown and poor quality of these crops. (Figure 1) . Keep all ripe fruit harvested on a tight schedule, and refrigerate as soon as possible after harvest. If possible, remove unmarketable fruit from the field.
Products registered for spotted wing drosophila control on berry crops include Malathion and Delegate. Mako, formerly named Ripcord, is registered on strawberries and raspberries but not blueberries and is labelled for “suppression only” for SWD. See www.ontario.ca/spottedwing for current registrations.
Exirel is fully registered on blueberries and other bushberries for SWD control. Bushberries include haskaps, saskatoons, sea buckthorn, currants and blueberries.