WSU Works with Multi-State Team to Combat Spotted Wing Drosophila

PROSSER, Wash. — Fueled by a $1.2 million USDA Specialty Crops Research Initiative grant, Washington State University has mobilized a large interdisciplinary team of scientists and Extension educators to try to beat back the rapid encroachment of spotted wing drosophila.

Washington State University entomologist Doug Walsh holds a fly trap. Photo: WSU. Click image for high-resolution version.

First introduced into California in 2008, SWD is a red-eyed “vinegar fly” that attacks ripening fruit as well as rotting fruit. The fly has rapidly spread northward along the Pacific coast into Oregon and Washington and is considered a serious threat to Pacific Northwest fruit crops such as cherry, raspberry, blackberry, blueberry, strawberry, plums, pluots and nectarines. Recent evidence indicates that spotted wing drosophila is also a threat to wine grapes.

WSU’s team of experts is led by veteran entomologists Doug Walsh and Lynell Tanigoshi. Both are professors in the Department of Entomology. Walsh is located at the WSU Irrigated Agriculture Research and Extension Center in Prosser. Tanigoshi is located at the WSU Northwestern Washington Research and Extension Center in Mount Vernon.

“To date SWD is still an Eastside vs. Westside issue. We’ve had traps out since early March east of the Cascades in Benton, Franklin, and Walla Walla counties and we appear to still be free of SWD infestation. On the Westside, scientists have observed SWD adult flies all winter.”

Walsh noted that climate models predict that the cold winters and especially the hot dry summers of the Columbia Basin, Wenatchee, and Walla Walla Valleys may prove to be outside the preferred geographic range of this pest insect. “SWD is certainly a fair weather fly.” SWD prefers the coastal climates and, in Washington, SWD developmental models predict that areas such as the Skagit Valley are the most hospitable for SWD.

On the west side of the state in Mount Vernon, Tanigoshi is in Washington’s ground zero for SWD. He and his staff have been busy all winter developing recommendations for western Washington’s small fruit producers, including growers of raspberries, blueberries and strawberries, who will be impacted by SWD. “Selective insecticides are our first defense,” Tanigoshi said. “But our soft fruit growers must walk a fine line between controlling SWD with insecticides and possibly killing the essential honey bee pollinators required to produce these small fruits.”

WSU is part of a multi-state pest management program for SWD funded by a $5.7 million USDA Specialty Crop Research Initiative grant. Other participating agencies include Oregon State University, the University of California, and the USDA Agriculture Research Service.

Tanigoshi and Skamania County Extension Educator Todd Murray have mobilized their efforts and conducted a series of well-attended grower workshops to inform Westside growers about SWD monitoring and control.

WSU Eastside entomologists Walsh and Elizabeth Beers, who is based at the Tree Fruit Research and Extension Center in Wenatchee, and regional Extension educators Tim Smith and Gwen Hoheisel are warily monitoring for SWD while hoping for the best.

Smith and Beers have spent their careers developing effective integrated pest management programs for pests of tree fruits in eastern Washington. In particular, they have been extremely successful in developing a control program for Western Cherry Fruit Fly based on nontoxic bait called GF-120.

“We don’t want our growers to get off this effective program and spray potentially disruptive insecticides for SWD control until we have solid proof of SWD infestations in eastern Washington,” Smith said.

Other WSU faculty involved in the SCRI project include small fruits specialist Tom Walters and organic production specialist Carol Miles in Mount Vernon, and cranberry specialist Kim Patten in Long Beach. On the urban and homeowner front lines are Carrie Foss, WSU Urban IPM Coordinator in Puyallup and Statewide Master Gardener Coordinator, Toni Fitzgerald.

Walsh, who serves as the state’s Integrated Pest Management Coordinator quipped, “I’ve assembled the group I call my usual suspects. We’ve got a great team put together. We’ve mobilized on all fronts to get out ahead of this pest and, with this influx of SCRI funding, we now have the resources to combat it effectively.”

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