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Light-Brown Apple Moth Found in Carneros

Area faces quarantine if a second moth is found; some residents oppose measures to control potentially devastating vineyard pest

Lynn Alley
Posted: August 18, 2008

According to Sonoma County agriculture officials, a single light-brown apple moth was discovered Aug. 13 in Carneros, close to the Napa County line.

This is the third moth found in Sonoma County this year. While the first two were found in an area northwest of the town of Sonoma this past spring, the latest find was in an area further to the southeast that is home to many vineyards.

Should another moth be discovered within a mile of the latest find, county and state officials will be forced to quarantine the area, restricting the movement of flowers and fruit at a time when growers are scrambling to bring in the harvest.

The day after the discovery, officials at the California Department of Food and Agriculture (CDFA) placed traps within a 9-square-mile grid around the find in an effort to determine whether there are other moths.

Nick Frey, executive director of the Sonoma County Winegrape Commission, said that if a quarantine is enforced, growers will need to have their vineyards examined by agriculture officials within 30 days of harvest. If no insects are found on the property, officials will supply each shipment of grapes leaving the area with a written statement certifying the vineyard to be moth-free.

The light-brown apple moth, native to Eastern Australia, was first sighted in California near Berkeley in 2007. State agriculture officials believe it could have a potentially devastating impact upon California agriculture. It has a potential host range of more than 2,000 plant species, including crop plants such as grapes and citrus fruit, and trees such as redwoods and oaks. In the vineyard, moths lay eggs on grape leaves and the larvae feed on leaves and fruit clusters, leaving them prone to rot.

A plan to set pheromone-soaked twist ties that disrupt the mating behavior of the insects in the quarantine area was scrapped last week by state and county officials, partly because no moths have been discovered in the area since last spring, and partly due to resistance from local residents who feared the twist ties might have adverse health effects. The quarantine was due to end in early October, provided no new moths were found in the area.

Earlier this year, a light-brown apple moth control program which would have entailed aerial spraying of hormone-disrupting pheromones over parts of the San Francisco Bay Area, Monterey and Santa Cruz counties met with vigorous and organized resistance on the part of residents, health professionals and environmental groups, many of whom claimed to have become ill as a result of aerial spraying last year.

Steve Lyle, spokesperson for CDFA, said that agriculture officials have now abandoned plans for aerial spraying of the state in favor of a new program in which large quantities of sterilized insects will be released so that the wild population cannot reproduce.

According to Lyle, the sterile insect-release program is slated to begin sometime next year, and will become the predominant approach to control and eradication of the insect. Lyle says smaller areas of infestation will still be targeted with pheromone-soaked twist ties aimed at disrupting the insect's mating cycles, and that education of the public regarding the safety of the ties will be a key component.

As for the Carneros wineries, T.J. Evans, winemaker at Domaine Carneros, summed it up. "Let's just hope this guy made a wrong turn on his way to somewhere else."

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