Trapping for spotted wing drosophila
University researchers offer guidelines for managing a new pest problem.
Spotted wing drosophila
Oregon State University researchers have compiled integrated management guidelines to prepare Pacific Northwest growers for what could be a new pest in their cherry orchards this season—the spotted wing drosophila. The new species of vinegar fly was found in a large number of crops on the West Coast last year, including Oregon cherry orchards in Hood River, The Dalles, and Milton-Freewater postharvest. Growers in Oregon’s Mid Columbia region will soon learn if the fly was able to overwinter and become established.
The guidelines are a series of slides that cover identification of the tiny fly, how to make monitoring traps, when and where to trap, checking fruit for spotted wing drosophila larvae, and integrated management practices. OSU scientists have developed a list of preferable insecticides to use against the pest.
To learn how to identify the fly and make monitoring traps, view OSU’s Spotted Wing Drosophila handout. A detailed review of insecticides available is contained in OSU’s SWD Guidelines for Oregon Cherry Growers.
Trapping for the spotted wing drosophila should be initiated before cherries turn straw color to allow time to treat the pest before it damages fruit, according to new research conducted by University of California scientists. Choice tests conducted with Brooks and Tulare varieties have found that the spotted wing drosophila will infest fruit that are straw colored and have started to soften.
Reports have also been received from a few California cherry growers of malathion phytoxicity. Dr. Robert Van Steenwyk, UC-Berkeley, believes the problem, which has shown up in some blocks but not others, may be related to tree maturity, with phytotoxicity showing up in young trees with rapid foliage and fruit growth. Van Steenwyk advises growers to do a small trial (10 to 20 trees) spraying different formulations of malathion before treating the entire orchard. Van Steenwyk has compiled monitoring and treatment recommendations that can be viewed here: Spotted wing drosophila recommendations for sweet cherries.