Spotted wing drosophila (SWD) is an invasive fly from Asia that attacks a wide range of soft-fleshed fruits, including berries, grapes and cherries. While most flies will only attack damaged or rotting fruit, SWD can lay its eggs in healthy, ripening fruit therefore leading to a much greater risk of contamination of fruit with SWD larvae at harvest. SWD will attack haskap, however in many years haskap escapes significant damage because SWD populations do not typically increase until later in July, after haskap harvest has ended.
Traps have been set up to monitor for this insect in various berry crops in several areas of Ontario this year: Norfolk, Elgin, Middlesex, Chatham-Kent, Niagara, Waterloo, Wellington, Dundas and Renfrew counties and Temiskaming District. Last week, the first SWD of 2023 were found, with 1 SWD caught in each of five counties.
Summary of SWD trap catches:
|Week traps collected||County/region where SWD was found||Crops where SWD was trapped|
|July 1-7||Elgin, Oxford, Waterloo, Middlesex, Chatham-Kent||Wild hosts, currants, strawberries|
Monitoring is funded by the Berry Growers of Ontario. Thanks to the growers, consultants and OMAFRA staff helping with this monitoring!
Once SWD is found in area, all berry crops are at risk, regardless of where traps have been placed. Finds from last week indicate SWD adults are starting to move from wild hosts to crops. Fortunately, haskap harvest is nearing completion in many areas so berries may escape significant damage. However, growers in areas where SWD has been found who still have 2 or more weeks before harvest is complete should consider controls.
Management strategies for SWD involve a combination of cultural and chemical controls. Do not rely on sprays alone – use as many of these tools as possible.
- Spray every 5-7 days if berries will not be harvested for 2 weeks or more. For a list of products registered on haskap visit the Ontario Crop Protection Hub and select haskap, then SWD in the drop down menus.
- Keep fruit picked regularly and clean – this can be very effective
- Cool fruit immediately after harvest
- Keep alleys and base of plants clean – either remove unmarketable fruit or crush it
- If unmarketable fruit is being removed, it should be destroyed (dispose of it or leave in plastic bags in the sun)
- Make the environment less favourable to SWD – prune the canopy and/or manage water to reduce humidity (e.g. repair leaking drip lines)
Growers should also consider monitoring on their own farms ; to monitor you can use sticky cards to identify adults, or salt water tests or plastic baggie tests to monitor for larvae. When infestation is very severe, damaged berries may also be visible on the plant.