Spotted Wing Drosophila (SWD) Update – July 15, 2016

SWD numbers continue to increase. More sites are positive and more SWD are being trapped. This past week we have seen a big jump in SWD numbers in Essex County. So far our trap captures have been mostly in southern Ontario, but this past week we found the first trap capture in Durham region. Also, more SWD are being trapped in crops, not just the wild hosts around the farm.

We have trapped SWD in the following counties and regions: Essex, Kent, Middlesex, Oxford, Norfolk, Waterloo, Brant, Elgin, Haldimand, and Niagara and Durham regions.

Fruit which is ripening in these areas, and anywhere else in southern Ontario, is at risk for SWD damage.  SWD should be managed by picking fruit early, thoroughly and often. Sweet cherries, sour cherries, raspberries and blueberries will be attractive to SWD at this time, as well as strawberries.  A list of registered insecticides for SWD can be found here:  Ontario.ca\spotted wing – products registered for SWD . Weekly sprays will help keep SWD under control, and will be required blackberries, fall-bearing raspberries and day neutral strawberries later in the season.

During this early stage, as SWD populations begin to ramp up, there are still many questions about when to start spraying.  Salt water assessments of harvested fruit should be done routinely as an early warning of SWD problems.

In summer fruiting raspberries, growers have typically managed SWD with few problems by harvesting thoroughly every day or two. However, a pre-pick spray in late varieties may be required.  A postharvest spray on raspberries is a good idea if fruit is left behind as you move from one variety (i.e. Prelude) to the next.

In fall bearing raspberries, SWD can build up on the early fruit at the base of the cane. If you are not harvesting this fruit, consider removing it or at least direct a nozzle to the base of the canes and start an insecticide program now on fall bearing varieties.

Blueberries are ripening. Apply a pre-harvest insecticide for SWD to later varieties now as you harvest Duke and early varieties. Exirel will control both SWD and Japanese beetle.

Strawberries should be mowed and renovated as soon as possible after harvest. Mowing strawberries will help fruit to dry up and make it less attractive to SWD.  Growers who are renovating strawberries do not need to spray for SWD unless they have raspberries or blueberries or other susceptible fruit close by.  Cygon or Lagon, when sprayed to control aphids in strawberries, is also toxic to SWD flies, and would be a good choice at renovation.

As cherries colour they will become more attractive to SWD.   Consider using an insecticide that controls both cherry fruit fly and SWD in pre-harvest sprays. Delegate, Entrust, Success, Exirel, and Silencer would likely control both pests, if the timing and coverage are good.

Table #1: Summary of Spotted Wing Drosophila (SWD) Trap Captures

• 2016 Registrations http://www.omafra.gov.on.ca/english/crops/facts/swd-registrations.htm
• Printable version: https://onfruit.ca/wp-content/uploads/2016/06/registration-for-swd-june-2016.pdf

See www.Ontario.ca/spottedwing.

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