Two years of testing and trapping have shown the European grapevine moth no longer is present in Fresno, Mendocino, Merced and San Joaquin counties, meaning the quarantines in those areas can be lifted, the U.S. Department of Agriculture plans to announce Tuesday.
"That's obviously very good news for the folks here in the Central Valley," said Barry Bedwell, president of the California Grape and Tree Fruit League. "Our focus now is on that core area in Napa where it still exists."
The department's Animal and Plant Health Inspection Service says removing the quarantines means exports of host commodities such as grapes and stone fruit from those counties can resume to Mexico without additional inspections, treatments or special packaging markings that have cost growers an estimated $10 million a year.
"It means we no longer have to jump those regulatory hoops to ship," Bedwell said.
Mexico is one of California's top five export markets for table grapes and the third largest importer of stone fruit.
Quarantines remain in effect in Napa, Solano, Sonoma, Santa Clara, Santa Cruz and Nevada counties.
The bug managed to destroy an entire Napa County vineyard's crop at peak harvest time before anyone recognized the new invader in September 2009. Detection of the moth — one of the grape industry's most feared pests — triggered an aggressive state and federal eradication campaign to keep it from taking hold.
Intensive spraying and a quarantine that restricted movement of fruit and equipment failed to contain the voracious eater, which quickly spread into neighbouring Sonoma County. A year later the moth spread to the southern Central Valley, before spreading out to the coast and a small area of the Sierra foothills.
Scientists from France, Italy, Chile and Germany travelled to California to help form an eradication plan.
As the weather warms and larvae emerge from eggs laid last year, traps in Napa County have shown few bugs, which Bedwell hopes will mean the eradication of the moth in California's premiere grape-growing region and the eventual lifting of all quarantines.
Nobody yet knows how the moth got here, though some suspect it hitchhiked in on smuggled grapevine cuttings.