The Pacific Northwest Pest Alert Network reports the Western Cherry Fruit Fly appeared in southwest Idaho and the Mid-Columbia River region in Oregon.
On May 22 the first report of a Western Cherry Fruit Fly captured in a Idaho State Department of Agriculture species-specific trap in Canyon County. Network officials said that historically, the fly appears in Gem County about a week after the first specimen is found in Canyon County.
The fly was also found May 20 at the Oregon State University Mid-Columbia Agricultural Research and Extension Center station in Hood River.
Growers should start treating for the flies immediately, the recent alert said. White maggots infest cherries, and the mature maggot makes a hole in the cherry as it exits.
Online phenology and growing degree-day models for the Western Cherry Fruit Fly predicted the first flight on May 21 in Ontario, Ore., and Parma, Idaho; and also in Idaho May 24 in Caldwell, May 25 in Emmett, May 29 in Boise and May 31 in Nampa, the network said.
Recommended strategies for growers include spraying one of about seven selected chemicals through harvest, at seven- to 10-day intervals, and growing early-maturing varieties.