The spotted-wing drosophila (SWD), an invasive fruit fly that threatens blueberries, raspberries and other fruit crops, has just been found in St. Lawrence County. Dr. Juliet E. Carroll of the NYS Integrated Pest Management Program at Cornell confirmed that an insect caught in a monitoring trap near Canton on August 25 is a female SWD.
Because this Asian pest lays its eggs in firm, ripening fruit rather than in soft over-ripe fruit, SWD can cause severe damage in commercial and home fruit plantings. It first appeared in North America in California in 2008 and has since spread across most of the continental US as well as parts of southern Canada.
Where SWD is concerned, it would appear that for the colder parts of NYS there might be a little good news, or at least less bad news. Spotted-wing drosophila does not seem to be able to overwinter in the North Country, but instead must migrate northward over the course of the season. Because this is such a new pest, it is not yet clear where the northern limit is for its winter survival.
In 2012, the first year SDW hit hard in New York State (it was found in very small numbers in central NY in October 2011), many fruit growers throughout the state suffered total or near-total crop failures. However, losses in both 2013 and 2014 are down compared with the initial infestation.
Furthermore, spotted-wing drosophila has appeared later in the season each successive year thus far.
The statewide network of monitoring traps was not yet in place in 2012, but anecdotal reports indicate SWD arrived in St. Lawrence County around August 12 that year. In 2013 it was found on August 20, and this year it was the 25th of August.
There’s no way to tell if this trend will continue, but the later SWD arrives in any given year, the less damage it can do to blueberries, day-neutral (everbearing) strawberries and summer raspberries. Fall raspberries will remain vulnerable to the pest, though.
Management strategies include field sanitation, frequent and close picking, as well as insecticide applications. For more information, see www.fruit.cornell.edu/spottedwing/ or www.nysipm.cornell.edu/invasives_exotics/swd/swd.asp on the Internet, or call your Cornell Cooperative Extension office.