Growers doing better job of SWD control Research continues into
how fruit pestmanages to survive winter cold. By Judie Steeves
T
here still aren’t many products available for control of Spotted Wing Drosophila, but at least the numbers were low last year in the Okanagan, reports agriculture ministry entomologist Susanna Acheampong.
She says she is not aware of any commercial damage done to crops last year by the new Asian pest of soft- skinned fruits, but the numbers did spike as the harvest came to an end. “Growers are doing a much better job of controlling the pest,” she commented.
Other than that, she said no one is sure just why numbers were lower this past season. Acheampong says she’s hopeful the early fall cold spell could have an impact
on numbers for the coming year, but it’s still too early in the battle against SWD to relate their overwinter survival to weather.
“In the Okanagan we’re still trying to determine where they hide overwinter,” she said, although it seems certain it’s in the wilder areas around farms.
Research
continues into overwintering habitat, and into
possible commercial parasitoids or predators that could be used for control, she noted.
When the SWD was first discovered in the Pacific Northwest in 2008, the literature indicated it could not survive cold Okanagan winters, but it found warmer areas around buildings and it did survive.
SWD is a vinegar fly that can devastate soft fruits and berry crops, including cherries, peaches, apricots, nectarines, plums and grapes.
As soon as fruit ripens—not just when it’s overripe—female SWD adults will lay eggs on the fruit in holes they excavate through the thin skin. Eggs hatch in 12 to 72 hours, depending on the temperature and the female fly can lay 20 to 30 a day, several eggs per fruit.
In five to seven days, the larvae feed on the fruit, rendering it soft and inedible, and they then emerge as adult flies so they can mate and repeat the cycle, several times a season.
Fruit that’s infested becomes a breeding site, so it’s vital that growers pay close attention to sanitation in the orchard or vineyard, and carefully dispose of all fruit, she warned. Another invasive alien pest Acheampong says they ask growers to be on the lookout for, is the Brown Marmorated Stink Bug, which also can have a devastating impact on fruit, and which has already been found south of the border, in Washington State. It has not yet been detected in B.C.
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British Columbia FRUIT GROWER • Winter 2014-15
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