Spotted Wing Drosophila

Asked February 1, 2013, 4:25 PM EST

Last year I found my raspberries were infested with SWD which I had never heard off prior to the identification by county extension. What are the current control methods at this time? When do I start control efforts? Does trapping have any useful indications in control?

Clackamas County Oregon

1 Response

Thank you for your question to Ask an Expert about managing SWD in your raspberries. Yes, monitoring/trapping is an important part of SWD management. You should begin monitoring when the average temperature is above 50 degrees or you start to see a blush of color on your fruit (end of May to mid-June). You'll find information about SWD in this publication:

Protecting Garden Fruits from Spotted Wing Drosophila http://horticulture.oregonstate.edu/system/files/em9026_0.pdf

You’ll find additional information at the official SWD site http://horticulture.oregonstate.edu/group/spotted-wing-drosophila.

Once you arrive at the main page, click on “Noncommercial/Gardeners" on the right side of the page.

The bottom line for SWD management is that it requires a combination of various tactics:
1. Sanitation – Collect infested fruits (on the tree, vine, canes or ground) whenever you see them; place in a securely closed plastic bag then set in the sun for at least 6 hours.
2. Exclusion - Net the fruit, entirely or in part with inexpensive tulle (fabric for wedding veils)
3. Harvest promptly; better yet, a bit early.
4. Trap – You can easily make traps from materials you likely have at hand which will help reduce the population as it can grow at a mind boggling rate. The best baits are either apple cider vinegar or white wine. (Regular white vinegar doesn’t work.) The SWD page has the specifics, as well as brief videos for making traps; placing traps; and more.
5. Pesticides, organic or not, are considered a last resort. Active ingredients available to home gardeners are listed in the above linked document. When using pesticides of any sort, always follow the label’s directions exactly.

If you have suspected infected raspberries this year, please bring some samples to:

Clackamas County Master Gardener office
200 Warner–Milne Rd.,Oregon City, OR 97045
Hours: 9 AM – 12 Noon and 1 PM – 4 PM, Monday – Friday
Phone: 503–655–8631 Email: clackmg@oregonstate.edu Thank you for your inquiry. If you have further questions, please ask.