Cherry orchardists wary of new pest

Hundreds and hundreds of farmers throughout the Okanagan and Similkameen Valleys have been turning out this week to information meetings about a devastating new pest of cherries and other soft fruits.

Hundreds and hundreds of farmers throughout the Okanagan and Similkameen Valleys have been turning out this week to information meetings about a devastating new pest of cherries and other soft fruits.

The vinegar fly, spotted wing drosophila, first showed up in Canada in the fall of 2009, but by last fall, there were millions, and some growers’ cherries were turned away from the packinghouse, which has a policy of permitting no worms.

However, growers were assured that by following the recommended regimen of applying cover sprays in the orchard, and cleaning up after harvest, control of the invader is possible.

Key advice from Wednesday’s Kelowna workshop, where researcher and entomologist Peter Shearer described the Oregon experience with SWD last year, is “growers must not be complacent. They must remain vigilant.”

That advice was repeated by Charlotte Leaming, field staff with the Okanagan Tree Fruit Co-operative, who warned the pest is “everywhere.”

She advised that everyone growing soft fruit has to deal with alternate hosts of SWD, such as berries in the home garden or those of neighbours, wild blackberries, saskatoons and Oregon grape, and also fruit that is not shipped.

Cull fruit must be properly disposed of, not in the compost, but by burying it or freezing it first; and she advised that such holes be dug prior to the busy time of harvest, so there’s no time lag.

There’s a very short time between the first hatch of adults and the first egg laying in fruit. It can be as short as a day, depending on temperatures.

Shearer told growers last year Oregon’s cherry-growing region was the only one in the west with no damage to cherries from SWD, and he’s confident with proper management, damage can be prevented. However, he admits that even Oregon State this year is gearing up for a major offensive.

Shearer told about 140 growers in Kelowna there are large, contiguous cherry orchards in the Columbia area of Oregon, which they treat by applying Malathion from an aircraft.

With the Okanagan’s smaller orchards, interspersed with residential areas and other farms, such an approach would not be practical.

Last year, Shearer said no flies were detected prior to the cherry harvest, yet they were still catching flies in traps after the first major freeze of the year in late November, and during the thaw in January, so he knows things will be different this year.