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Brown Moth Triggers Sonoma Vineyard Quarantine

Agriculture officials will inspect all grapes leaving area for infestation

Lynn Alley

Posted: Wednesday, May 14, 2008

An unwanted guest has brought a quarantine crashing down on 2,500 acres of vineyards in Sonoma County. State and local officials imposed the measure after a second light-brown apple moth was discovered near the town of Sonoma. Anxious growers are worried about the impact of the quarantine, which mandates that no fruit or flowers can be removed from the zone without state inspection.

First identified in the San Francisco Bay Area in March 2007, the moth, native to eastern Australia, is seen as a potentially devastating predator for California crops. It has a host range of more than 2,000 plant species and 250 crops such as grapes, citrus and deciduous fruits. In addition, it poses a threat to the state's heritage redwoods and oaks. In vineyards, the insect lays eggs on vine leaves and hatching larvae damage grapes as they feed, triggering rot.

On Feb. 26, a single moth was discovered in Sonoma County. On April 21, a second moth was found, triggering a designation of "infested" for the area. The California Department of Food and Agriculture (CDFA) and the Sonoma County Agriculture Commissioner's office quarantined a 15-square-mile area, including 2,500 acres of prime Sonoma Valley vineyards.

Traps have been placed throughout the area to determine if there are more moths there and, starting in June, the CDFA will place pheromone-soaked twist ties within a 200-meter radius of each find in an effort to eradicate the insect. The twist ties disrupt the moths' mating patterns and are currently the treatment of choice for small infestations, according to Stefan Parnay, chief deputy agriculture commissioner in Sonoma County.

Aerial spraying of synthetic pheromones for control of larger moth populations have triggered protests recently in the San Francisco Bay Area, as well as in Monterey and Santa Cruz counties, where aerial sprayings occurred last year and some residents complained of respiratory and digestive ailments. Parnay said no aerial spraying has been planned at this time for Sonoma, due to the very limited nature of the infestation there.

For grapegrowers and other farmers, the quarantine is a more immediate concern. The county and CDFA have a choice of inspecting each individual shipment of grapes destined for locations outside of the quarantine area (most grapes grown within the delimited area are utilized in wineries outside the area) or inspecting vineyards within 30 days of planned shipments to destinations outside the area.

Although the final determination as to methods remain in the hands of CDFA, at this time county agriculture officials are looking at plans to inspect the vineyards rather than individual shipments. "We'll be working with wine grape growers over the next few months to make sure there is as little adverse impact upon them as possible," said Parnay.

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