Spotted wing drosophila and haskap

Haskap is traditionally not thought of as having many pest issues beyond birds, however growers should be aware that it can be at risk from spotted wing drosophilla.  Spotted wing drosophila (SWD) is an invasive vinegar fly from Asia that has become a significant pest problem for a number of fruit crops in Ontario, including berries, grapes, cherries and other soft-fleshed fruits.  It is now considered to be an established, chronic pest throughout most of Ontario.  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.

While haskap is a potential host for SWD, it has generally escaped significant damage because SWD populations do not typically increase until later in July, after haskap harvest has ended.  In 2017, a mild winter led to an earlier increase in numbers of egg-laying females.  Additionally, delayed ripening of the Simcoe haskap crop led to harvest being pushed into July.  These factors seemed to create a perfect storm for SWD to attack haskap berries, leading to significant damage, with berries becoming completely unmaketable by mid-July.

Haskap SWD1

Haskap berries infested with spotted wing drosophilla.  Fruit damaged by SWD may be wrinkled, softened or have early mold.  

Haskap SWD3

Eventually, fruit skin collapses with a very wrinkled appearance that becomes very obvious about 5 days after egg-laying.  Note the SWD larvae emerging from these infested haskap.  Pink-prick sized scars or breathing holes may also be seen on damaged fruit.  

In 2018, SWD numbers are not increasing as quickly, while haskap harvest is proceeding at a normal schedule. As of this week, OMAFRA monitoring have detected adults in 4 counties (Essex, Chatham-Kent, Northumberland and Norfolk – see OMAFRA’s ONFruit blog for more details).  Simcoe haskap harvest  is almost complete and to date there has been no SWD damage detected.  Growers in more northern regions who have not yet completed harvest should be watching for damage from this pest.  Additionally, growers who are planting newer varieties with later harvest dates than the traditional B.T.I. (Borealis/Tundra/Indigo) cultivars should be prepared to monitor for this pest when crops come into production over the next few years, as the later harvested varieties may overlap with peak SWD egg laying activity.

Growers can get full details on SWD identification, monitoring and management on OMAFRA’s spotted wing drosophila webpage.  While cultural management practices are applicable to all berry crops, pest control product registrations for spotted wing drosophila are more limited on haskap than on other fruit crops.  Insecticides registered on haskap for the control of spotted wing drosophila are: Delegate (spinetoram), Entrust (spinosad), Exirel (cyantraniliprole) and Success (spinosad).  All other products mentioned for control of SWD are NOT registered on haskap at this time.



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