Orchardists fear vinegar fly infestation could result in millions of dollars lost


Capital Press

SALEM, Ore. -- Orchardist Stuart Olson was struck a few weeks back with the sudden appearance of what he thought was brown rot on his peaches.

The late-maturing Elbertas were clean just days before the sudden arrival of the rot and there was no indication rot was developing.

Olson put two and two together, started doing some research and before long realized it wasn't a rot. His peaches were being invaded by a pest new to the Willamette Valley.

A month ago, most Northwest farmers and regulators had never heard of the spotted-wing Drosophila suzukii. Olson is among the Oregon farmers, state regulators and entomologists who today have a heightened awareness of the tiny vinegar fly with a wide host range that feeds on fresh fruit.

Some fear the fly could emerge as one of the worst insect pests to invade the valley, and potentially the entire Northwest, in years.

"It couldn't come at a worst time for agriculture," Olson said. "With commodity prices where they are and this insect coming along, it has the potential to be very serious for agriculture in the state of Oregon."

The pest is highly adapted to Oregon's temperate climate; has a host range than includes wild blackberries; multiplies rapidly; and unlike fruit flies that feed on rotten fruit, the vinegar fly feeds on ripe and ripening fruit.

"Frankly, we think it is potentially a big deal," said Jim Cramer, administrator of the Oregon Department of Agriculture commodity inspection division. "And from a management perspective for these growers, it definitely is a big deal."

Olson fears that unless scientists and growers can devise a way to control the pest at a reasonable cost, growers could have an immense problem next spring when fruit starts ripening.

"It's a harmless looking little insect," Olson said. "But the economics of this thing could be millions and millions of dollars."

Present in Japan for decades, the Drosophila suzukii only recently has emerged as a concern in the United States. It is found in Hawaii, California, Oregon, Washington, British Columbia and Florida.

In Oregon, the pest reportedly has not been found in orchards in Hood River or The Dalles but has been reported throughout the Willamette Valley.

Olson's main concern is the fly's potential to dramatically increase his pest control cost and disrupt his existing integrated pest management program.

Females lay up to 400 eggs per life cycle, according to Helmuth Rogg, an entomologist with the Oregon Department of Agriculture, and the pest is known to have as many as 13 generations per year in Japan.

Olson said the pest went from a minor presence to an infestation in a matter of days on his farm. In three or four weeks, Olson said, 20 percent of his Elberta peaches in a 3-acre orchard were destroyed.

Rogg said the pest could be extremely difficult to control.

"We are concerned because we have lots of feral fruit like the Himalayan blackberry, so they can multiply around an orchard and infest an orchard from the feral fruit," Rogg said.

State officials, entomologists and farmers have more questions than answers, Rogg said, including how the pest reached Oregon and why it only now is emerging as a pest of concern.

Rogg said the pest is considered a "non-action, non-reportable pest." As such, shippers are not required to report its presence when importing fruit from Asia.

It was reported in California in 2008, but only became a pest of concern this past spring when "colossal infestations of the new vinegar fly in cherries were reported," according to the University of California Extension Service.

"There are lots of pathways for the drosophila to come in here," Rogg said.

"We're working with OSU (Oregon State University), the USDA Agricultural Research Service in Corvallis and we're researching literature and checking with other countries to see if we can do something about it," Rogg said.

The only good news, Cramer said, is most of Oregon's 2009 fruit crop has already been harvested, packed and shipped.


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