Spotted Wing Drosophila (SWD) Update – July 29, 2016

See www.Ontario.ca/spottedwing

• SWD numbers have increased dramatically.
• More sites with SWD
• More counties where SWD has been trapped (+Grey , Wellington, Peterborough, Northumberland)
• All ripening fruit at risk
• Huge increase in numbers of SWD, especially near June bearing strawberries, and wild raspberries.
• Damage detected in commercial fruit

More SWD are being trapped in crops, not just the wild hosts around the farm. We are now catching almost 100 flies per trap, another generation is emerging and damage to crops is definitely occurring. Low levels of damage have been detected in raspberries, blackberries and day neutral strawberries.

All growers should assume that SWD is present now. Fruit which is ripening is at risk for SWD damage.  SWD should be managed by picking fruit early, thoroughly and often. Keep fruit cold after harvest. Weekly sprays will help keep SWD under control and are now required on all ripening fruit. A list of registered insecticides for SWD can be found here:  Ontario.ca\spotted wing – products registered for SWD .

Salt water assessments of harvested fruit should be done routinely as an early warning of SWD problems. http://www.omafra.gov.on.ca/english/crops/facts/swd-saltwater.htm

In summer fruiting raspberries SWD is easy to find now. All ripening and ripened raspberries and blackberries are at risk. Keep a lid on the SWD problem by frequent harvest, weekly insecticides and cooling fruit ASAP after harvest. Postharvest insecticides are a good idea if there are fall bearing raspberries or blueberries adjacent to summer red raspberry blocks.

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. If this is not possible, direct a nozzle to the base of the canes and start an insecticide program now on fall bearing varieties where fruit is ripening.

Blueberries: Growers are busy harvesting early and mid-season varieties. Weekly insecticides for SWD are very important to help prolong harvest. Managing preharvest intervals can be difficult in blueberries, spraying blocks of varieties at different times can help. Growers are reporting good control of Japanese beetles with Exirel, which also controls SWD

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.

Day neutral strawberries– In new plantings, try to keep ripe fruit picked every 1-2 days and delay SWD sprays if possible. However, in overwintering fields, pressure is high and an insecticide program should begin now. Options include group 5 insecticides such as Delegate, Success, and Entrust, and group 1 insecticide – Malathion. Malathion for SWD will also control tarnished plant bug, and is a good choice now.  Avoid use of Mako (group 3) at this time, because it can lead to more problems with spider mites.   Mako will work well in cooler weather.

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

•  016 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