The European grapevine moth, a pest that last year destroyed the crop in a Napa Valley vineyard, has turned up in Sonoma County, agriculture officials said Thursday.
A single moth was found this week in an agricultural area near Kenwood, said county Agricultural Commissioner Cathy Neville. She would not disclose the location.
The discovery is the first outside of Napa County, where the pest was first found in the United States last September, a state official said. An estimated 50,000 traps are being placed this spring around California in search of the pest.
The find of a single moth doesn't trigger any quarantine or restrictions on growers. But the news proved sobering to farmers because the moth already has demonstrated its ability to damage grapes.
"I think it's alarming, but anticipated that we would have a find in the county," said Lex McCorvey, president of the Sonoma County Farm Bureau.
"I think the question is how manageable will this pest be and can we get ahead of the curve in managing it so that it doesn't have severe economic ramifications," McCorvey said.
The European grapevine moth is considered a much more serious threat to the state's grape industry than the light brown apple moth, a pest that became the focus of long-standing controversy after the state conducted aerial spraying in 2007 near Monterey.
The apple moth first showed up in Sonoma County two years ago, and at least a fifth of Sonoma County vineyards are now under quarantine. The pest can feed on leaves, buds and fruit of various plants, but to date no officials have reported damaged caused by the apple moth in Sonoma County.
In contrast, grapevine moths last Septemeber ruined a grape crop in an Oakville vineyard. The pests attacked the berries and infected them with botrytis, also known as bunch rot.
Last month the state placed a large swath of the Napa Valley under quarantine in response to the grapevine moth. The quarantine rules have yet fully to be spelled out, but Neville expects growers will be able to move their crops to market as long as they demonstrate they aren't helping the pest spread to new areas. Such rules would be similar to those for apple moth quarantines.
Except for slivers of Sonoma and Solano counties, all the 162-square-mile quarantine area for the grapevine moth lies within Napa County.
Pest management experts connected to the UC Cooperative Extension are watching the moth's life cycle in order to advise Napa growers on the best time to apply pesticides
A quarantine would be triggered in Sonoma County only if a second grapevine moth is found within three miles of the first find, and inspectors on Thursday were setting out more traps in that area, Nevile said.
The Kenwood moth was confirmed Wednesday, Neville said, within 24 hours of being found in a trap.
Jay Van Rein, a spokesman for the California Department of Food and Agriculture, confirmed that it is the first moth found outside of Napa County.
The moth, Lobesia botrana, is a native of Mediterranean Europe that is known to also exist in parts of Russia, Africa, Japan, the Middle East and Near East. It was first detected in Chile in 2008.
By the time the pest was confirmed there, it had spread to numerous locations within the country, said Lucia Varela, a UC Cooperative Extension pest expert who visited Chile this winter.
"That's what gives me stomachaches," Varela said.
In Chile, growers suspect the pest came in on harvest equipment brought from Europe. "But they never found a smoking gun" to confirm how the moth appeared there, Varela said.
The U.S. Department of Agriculture has a team investigating how the moth arrived in Napa, said Larry Hawkins, a department spokesman.
Some theories include the moth arriving on farm equipment or on cuttings that were illegally smuggled into the U.S.
Hawkins said the latter way "might be fairly unlikely" because the moth needs to lay its eggs directly on the grape flower or fruit. Nonetheless, he said the rules against smuggling exist to protect agriculture, and the team is looking for any answers that could help prevent future pests from entering the country.
The Kenwood moth may have entered the county directly from Napa, possibly in or on a vehicle, or it could be part of an existing infestation here. By putting out 25 traps per square mile near the site of the discovery, they hope to learn the answer.
Nick Frey, president of the Sonoma County Wine Grape Commission, said he was "disappointed but not surprised" by the latest discovery.
Asked if he expected more moths to turn up in Sonoma County, Frey said, "The fact that they found one doesn't give me a whole lot of confidence that they won't find another."
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