Tests show no vineyard pests in Washington

Capital Press

YAKIMA — The most extensive trapping for certain wine grape pests conducted by the Washington State Department of Agriculture has resulted in a clean bill of health.

The department trapped and took leaf and root samples at a total of 3,186 sites, from the San Juan Islands to the Columbia Gorge but mainly in the Eastern Washington counties of Yakima, Benton, Franklin and Walla Walla. Trapping went from the end of June into September, looking for four species of destructive moths, vine mealy bug and grape phylloxera.

Root samples were taken at 165 of the sites looking for grape phylloxera, an aphid-like pest that attacks grape roots and is considered the most serious grape pest in the world, said Mike Klaus, a WSDA entomologist in Yakima.

“We looked for several species of pests and other diseases and everything was negative except for one old positive site for phylloxera near Wapato,” Klaus said.

It was found at that same site in 1988 and it was surprising more wasn’t found, he said.

A genetic analysis of root samples still is being conducted in Olympia and could show positive for phylloxera, but otherwise it looks like the pest just doesn’t do well in Eastern Washington, he said.

Phylloxera almost wiped out French vineyards in the 1880s and was detected in Washington vineyards in 1988, 1989 and 2002, Klaus said.

But it has never been severe in Washington and scientists at Washington State University believe it just doesn’t like Eastern Washington’s soils or dry climate, Klaus said.

“We suspect it’s out there at low levels,” he said, “but different grape varieties coming in could be more susceptible, so it’s good to check.”

The four species of destructive moths — European Grapevine Moth, European Grape Berry Moth, Grape Tortrix and Grapevine Tortrix — also were not found, Klaus said.

Pheramone traps were placed in most of the state’s 13 wine grape growing regions.

European Grapevine Moth was found in California’s Napa Valley in 2009 and became a serious threat.

In 2013, USDA’s Animal &Plant Health Inspection Service released $16.9 million in emergency funding to combat it. Mating disruption and other control techniques had some success, he said.

Ten counties in California have vine mealy bug but it has not been found in Washington, he said.

“If any of these pests were to become established here, they could pose a serious threat to our grape and wine industries,” Klaus said.

Washington wine grape growers do deal with leaf roll and grapevine red blotch, viruses that delay ripening, hinder color and sugar in grapes and result in higher acidity. They are acerbated by cool weather and were held in check this season by warm weather.

“Grapes are a relatively new crop in Washington, so we don’t have a lot of pests that are in older grape areas,” Klaus said. “That’s why we do vigilant monitoring. We might be able to mitigate some of these pests if we catch them early enough.”