John Griesbach, a phytosanitary consultant who has worked with the Oregon Association of Nurseries, shared with us the following information about a new pest:
An informational meeting was held September 22 in Salem to update growers on a new and damaging exotic pest, the spotted wing drosophila (Drosophila suzukii). The pest has been found this summer in numerous west coast locations and is causing significant losses in commercial orchards, berry plantations and U-pick operations. It has yet to be reported in nursery operations but fruit-bearing host plants can be susceptible to infestation. Spotted wing drosophila (SWD) is thought to be native to Japan and occurs in other Asian countries, Spain and Hawaii. Its first detection in the continental U.S. was in California in 2008. So far in 2009, SWD has been recorded in California, Florida, Oregon, Washington, British Columbia and Alberta.
This new exotic fly differs from other species of drosophila, also known as vinegar flies, as it attacks healthy, growing fruit on host plants, rather than attacking diseased or damaged fruit on the ground. Symptoms look much like a brown rot infection and the fruit can rapidly decay on the host plant. Host include many species of Prunus, Malus, Vaccinium, Morus, Fragaria, Rubus and Diospyros. Cherries, peaches and blueberries seem to be particularly susceptible. Losses in cherry orchards in California were as high as 30 percent in some locations this summer.
Control trials are underway and researchers hope to develop management recommendations before next year’s production cycle. Surveys to find the extent of the infestation in Oregon are underway and the Oregon Department of Agriculture is accepting samples for identification. The pest already appears to be wide-spread in the Willamette Valley and has also been found in Umatilla County. For information on sample submission, contact the ODA at 503-986-4636 or the Oregon Invasive Species Hotline at 1-866- 468-2337.
To date, no state, federal or international quarantines have been imposed on host plants or fruit. The USDA Plant Protection and Quarantine Service is urging all states to conduct a survey to determine the extent of the infestation but believes the pest to be widely established in the US and therefore will not take regulatory action. A review of other exotic drosophila is currently underway to determine if other damaging species exist and if some regulation at the federal level is needed. This update was provided by staff from the Oregon Department of Agriculture, Oregon State University and Extension Service and the Agricultural Research Service and Plant Protection and Quarantine units of the USDA. Pest alerts, pictures and other information on SWD can be found at: http://oregon.gov/ODA/PLANT/IPPM/index.shtml.