“Worst year on record” for spotted wing drosophila

KELOWNA — The rapid spread of the spotted wing drosophila has been downright scary for BC growers. Since arriving from Asia, the drosophila also known as the vinegar fly has managed to go from California and sweep across the continent in almost no time.

“In my experience it was the worst year we’ve ever had, there was a small issue here and there in previous years but not like this year almost every orchard they had the problem this year,” said Bill Sandher, a Kelowna orchardist. “It’s pretty scary. We don’t know what to do.”

The drosophila ravages crops by nesting in fruit, in particular berries and cherries, it’s also been seen in peaches. On the surface the fruit may look fine but inside it’s already rotting, the eggs quickly hatch and turn into maggots.
What makes this bug so unusual, however, is the pace at which it’s spread. Others pests can take decades to make its way across the continent, if ever at all, the drosophila has done it in only a few years.

“There’s many other insects that are infesting Washington state or other areas that haven’t reached here yet,” said Ken Salvail, a horticulturist. “but this one fly that entered…it’s spreading much faster than most insect pests.”

One way to combat this has been the use of insecticides, many growers like Sandher are hesitant because markets like Europe don’t buy fruits with certain sprays. The bugs also grow immune.

Experts say the only real weapon are cold winters but even that’s not happening.

“This fly is greatly affected by temperature not just in regular season but through winter months,” said Salvail. “So last winter was such a mild winter, we really didn’t get the cold temperatures like we should really get, so the population is quite large.”

BC’s blueberry industry is worth more than 170 million dollars, cherry’s 30 million.  While there are no hard figures for the losses this season, growers say it has been significant.

Now some reports suggest grapes may be susceptible to the fly. There have been no problems yet for BC’s burgeoning wine industry, but you can be sure grape growers will be watching for the drosophila in the coming years.