Grapevine Moth: Almost Gone, Not Forgotten

Napa eradication program took great strides against winegrape pest

by Jane Firstenfeld
european grapevine moth trap
In 2011, Napa County deployed almost 5,000 European grapevine moth traps and caught a total of only 111 moths. Photo courtesy of Shasta County Agriculture.
Napa, Calif.—Napa County and the rest of California is on the verge of eradicating the European Grape Vine Moth (EGVM), the invasive pest that first came to light in the North Coast in 2009 and spread rapidly the next year. Dave Whitmer, Napa County agricultural commissioner, sent an update this week thanking the local wine and grape industry for cooperating with quarantine and control requirements that have significantly reduced EGVM populations in the county and elsewhere.

“Without your efforts, we would not be at the threshold of eradicating this pest from Napa County and statewide,” Whitmer wrote. “However, while celebration of accomplishments to date is important, we must remain vigilant in the year to come and not give up before we have reached our goal: elimination of EGVM from Napa County and the state of California.”

He summarized the successful measures, which began with detection trapping. In 2011, Napa County deployed almost 5,000 EGVM rural and urban detection traps and caught a total of only 111 moths—94 from the first flight, 16 from the second flight and one from the third flight. In 2010, similar methods captured more than 100,000 moths. Statewide total EGVM detections were also down: In 2011, only 143 adult EGVM were detected statewide, a 99.9% reduction from the previous year. New discoveries of the moths in Nevada and Santa Clara counties prompted quarantines to be established there.

In addition to detection activities in Napa County, the California Department of Food and Agriculture (CDFA) conducted treatments in urban areas where EGVM was detected in 2010. Aimed at reducing the overall size of the quarantine area, treatment started at the southern edge of the Napa County quarantine boundary and moved north, gradually shrinking the quarantined area by removing 1,300 pounds of grapes from 82 properties and deploying 131,281 mating disruption dispensers on 1,651 properties. “CDFA has received good cooperation from Napa County residents,” Whitmer said.

Quarantine compliance
The EGVM program asked growers to update their compliance agreement exhibits in 2011, and county inspectors verified compliance at vineyards and wineries during harvest. With the California Highway Patrol Truck Inspection unit, the ag commission staff conducted EGVM compliance inspections on trucks hauling grapes within Napa County.

“We set up inspection stations on Silverado Trail near Hardman Avenue and on Highway 29 at Rutherford Cross Road. On both occasions we issued Notices of Violation to haulers that did not have compliance agreements” and for improper loads, Whitmer reported. Grapes on truck beds or missing paperwork resulted in educational calls to the businesses involved.

“Overall compliance was high, and it is apparent that industry is doing a good job in preventing the movement of EGVM to other parts of the state and the nation,” Whitmer said.

“The low numbers of detection and high compliance with quarantine requirements demonstrate the great work and cooperation put forth by industry in dealing with EGVM. Together we have made great progress and are all very encouraged by these results! But, we cannot let up. We need to maintain our efforts over the next couple of years to reach the goal of eradication,” the commissioner insisted.

The Napa Valley Grapegrowers, which disseminated Whitmer’s report, thanked his team and others for their help, including University of California extension advisor Monica Cooper and grower liaison Martin Mochizuki for their service in the battle against EGVM in Napa County.

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