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Spotted Wing Drosophila, Spinach Seed

Posted by | November 17, 2010

Spotted Wing Drosophila Update

A male spotted wing drosophila (Drosophila suzukii)
A male spotted wing drosophila (Drosophila suzukii). Photo: Wikimedia/M. Francisco

In Washington’s berry fields, a new pest has migrated north from California and is now causing headaches for small-fruit growers.

Spotted wing drosophila, or SWD, infests soft fruits with its eggs, ruining the fruit’s market value. 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.

Named for the spots on their wings, SWD was first discovered in Washington state infesting strawberries growing in Puyallup. Since then, scientists at WSU, in collaboration with researchers in California and Oregon, have strived to provide farmers with methods to protect their crops from damage, while trying to understand the life cycle of the fly.

Lynell Tanigoshi, an entomologist at WSU’s Northwestern Washington Research and Extension Center in Mount Vernon, said understanding the fly’s biology and how it fits into the ecology of Washington state is key to managing the pest.

“This is the first season we’ve studied this insect, so we don’t yet have an idea of what the economic impact is going to be,” said Tanigoshi.

Unlike other flies that infest fruit already fallen to the ground, the SWD infests healthy fruit while still on the plant. The female deposits eggs inside the fruit.

According to Tanigoshi, until the arrival of SWD, most of Washington’s fruit pests were indirect pests, damaging foliage, stems or roots rather than the fruit. SWD is the first direct pest of small fruits and directly damage fruit in western Washington.

“We feel that there are probably populations that are adapting to the climate and some of these, I think, will be the progenitors of populations that may adapt, certainly to the west side of the mountains, but also into our high-value grape, blueberry, and cherry industries on the east side,” said Tanigoshi.

Tanigoshi said the primary focus of the current research is to provide the berry industry with effective means for controlling SWD. Research is currently addressing a wide range of production methods, from organic to a conventional, but it’s going to take time to really understand how the flies’ life cycle can be exploited in order to manage the pest.

by Matt Haugen, WSU News Services

For more information about spotted wing drosophila management efforts, please visit http://bit.ly/d2IM4K.

A video related to this story is at http://bit.ly/cgP4di.

Beating the Wilts

Fusarium attacks economically important seed crops in the Pacific Northwest.
Fusarium attacks economically important seed crops in the Pacific Northwest.

Rows of small black pots sit on moveable metal tables inside a greenhouse at the WSU Northwestern Washington Research and Extension Center in Mount Vernon. Warm air inside the greenhouse is nurturing spinach seedlings in the wet and rainy Skagit Valley. But a disease is attacking some of the plants, and WSU researchers are working to figure out ways to stop it.

The culprit, a soil-dwelling microscopic fungus called Fusarium wilt, is responsible for a decline in available land for spinach seed production in the Pacific Northwest.

Ph.D. student Emily Gatch is working in the lab of plant pathologist Lindsey du Toit developing tools to detect and combat the fungus. The work starts with a bucket of soil from a field slated for a spinach seed crop. Gatch and du Toit have developed a greenhouse soil assay that indicates which soils are at high risk for Fusarium wilt.

“It’s important that we have a secure spinach seed supply and that we are able to produce seed for growers throughout the country who are relying on Washington as their source. If you’ve eaten the bagged baby leaf spinach you can get in a grocery store, chances are the seed for that crop came from this valley,” said Gatch.

Washington is a major producer of vegetable crop seeds, including spinach.
Washington is a major producer of vegetable crop seeds, including spinach.

Soil testing identifies locations where spinach can be safely grown. Fusarium wilt is so devastating that once an area is impacted, spinach can’t be successfully grown again in that field for up to 15 years.

Hopefully that will change, said Kirby Johnson, president of the Puget Sound Seed Growers Association. A fourth-generation farmer in the Skagit Valley, Johnson said the work WSU is doing is critical to the livelihood of growers and their families.

“We need to find a way to get the crop rotation interval down from 15 to 16 years to 4 or 5 years, because we’re running out of ground,” said Johnson.

Gatch said that if researchers understand the ecology of Fusarium wilt in the soil, that information might translate into protection for other crops threatened by the fungus as well.

“This is a big deal,” Johnson said. “This research is tax dollars at work. It makes sense, and it makes money for the industry and for the farmers — and that’s important.”

by Matt Haugen, WSU News Services

For more information about WSU’s spinach research, please visit http://bit.ly/cNxhdd.

A video related to this story is available at http://bit.ly/94YZdT.