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UKIAH -- Thirteen European grapevine moths, which can destroy whole crops in certain stages of development, were found in a vineyard in north Ukiah, expanding the fight against the grape cluster pest from Napa, Sonoma and Solano counties.

Ten adult moths found in a trap on Monday and three more on Tuesday were positively identified by a state lab, according to Tony Linegar, Mendocino County agricultural commissioner.

"We hoped that if we found any in Mendocino County we would find two or three from winery waste from grapes brought in from Sonoma and Napa counties," he said. "With that many we may have a population established. This is what we believe is the second year for the moth in this county."

Grape larvae can survive harvest in unbroken or partially crushed grape berries and grow in the pomace piles.

It's still early in the moth life cycle, he noted.  It's about a month from when the first moth is found to when eggs are laid on the grape clusters, and the more damaging second and third stages of development would be coming in late May.

The moth was first found in the U.S. in September in Napa Valley, and more than 16,000 have been trapped there. A federal quarantine area was expanded last week to include 219 square miles around Napa and parts of Sonoma and Solano counties. Yet recent discoveries in Calistoga and Kenwood have expanded the potential quarantine area to include swaths of the Sonoma Valley and Knights Valley viticultural areas. Some officials suspect the moth has been in Napa Valley for five years to have that many moths found.

In Mendocino County the recent finds have brought in a response team of state agriculture regulators. Extensive trapping is set to start this weekend, focusing on the vicinity of wineries that have received fruit from Napa Valley, according to Mr. Linegar. Traps will be placed 16 per square mile, or about 650, throughout the winegrowing areas of the county.

At least three undisclosed vintners are in the initial watch area.

"This moth didn't fly up here from Napa Valley," he said. "If it's up here, it was moved."

Federal quarantine guidelines are still being developed by a 13-member team of experts and are expected to be released in about a month. Those guidelines could include a requirement to crush grapes in the same locale in which they're picked to prevent movement to other areas.

However, the guidelines for viticultural operations in quarantined areas are expected to include:

For grapes to be moved out of a quarantined area, the vineyard, especially the grape clusters where stages of the moth like to feed, would have to be inspected and shipment approved.

Grapes would be transported from vineyard to winery in covered trucks.

The grapes would be crushed immediately upon arrival at the winery.

Grape waste after crushing and pressing would be composted at a certified facility.

Many of these responsibilities are included in compliance agreements being issued by Napa and Sonoma county agricultural commissioners.

The high concentration of certified organic vineyards --- more than 3,000 acres in Mendocino County --- is causing concern about eradication methods, according to Mr. Linegar. However, he noted some compounds approved for use in certified-organic vineyards as well as options for using synthetic pheromones to confuse adult male moths in search of a mate are thought to be effective in fighting infestation.

Otherwise, insecticides would be used up to the time of verasion, or when grapes start taking on their mature color.

For more information, visit the Napa County Agricultural Commissioner's Office website page on the pest.