Moths' yen for grapes rallies ag into action

The hunt is on for a moth that feasts on grapevines and could threaten the Modesto area's wine industry.

The pest, the European grapevine moth, was detected in northeast Merced County last month and in five other California counties since last fall.

Officials hope to contain the bug with measures that include pesticides and quarantines, which regulate how grapes and other material are moved in the affected zones.

"It's very destructive in grapes," said Gary Caseri, agricultural commissioner for Stanislaus County. "It's quite a concern, and it's a pest that we certainly don't want in California."

The Northern San Joaquin Valley is among the state's leaders in grape acreage, mainly in the premium Lodi area.

Even more important are the wineries, which count on grapes from all over the valley and employ several thousand people. The big producers include E.&J. Gallo Winery in Modesto and Livingston, The Wine Group near Ripon, Bronco Wine Co. near Ceres, and DFV Wines, formerly Delicato, near Manteca.

Caseri's staff has placed more than 400 traps in and near vineyards, adding to a detection program that watches for numerous pests. No grapevine moths have turned up.

Three-quarters of the 1.03 million quarantined acres are in Napa, Sonoma and Solano counties. The rest are in Merced, Fresno and Mendocino counties.

Three moths were found near Snelling, prompting a 69,120-acre quarantine in a 5-mile radius that reaches to the Merced-Stanislaus county line.

The quarantine requires growers to coordinate with county officials when moving grapes, other crops that host the moth, or equipment that comes in contact with the crops. The pest does not fly far on its own.

People with backyard grapevines and other host plants are urged to consume the fruit at home.

Growers in affected areas also are urged to spray pesticides. They have to do this multiple times, because the moths can have as many as four generations over the growing season.

The controls are expensive but fairly simple, said John Monnich, owner of Silkwood Wines of Modesto, made with Stanislaus County grapes.

"Because of the life cycle of these pests, it's going to visit the fruit more often and require more (pesticide) applications," he said.

Growers also can use traps baited with a scent that mimics the sex hormones sent out by females to attract mates.

"What you end up having is a lot of frustrated male moths lying around and females not being mated and not producing eggs that are viable," said Greg Clark, assistant agricultural commissioner for Napa County, in a video on a state government Web site.

The U.S. Department of Agriculture has provided $3.7 million for efforts against the moth, which also threatens table and raisin grapes in the Fresno area.

After the moth was found in Fresno County last month, Mexico banned all crops from the county. That ban was later lifted.

"Our trading partners don't want the pest," said David Robinson, agricultural commissioner for Merced County. "We have to assure them we are not moving the pest."

Merced Sun-Star staff writer Carol Reiter contributed to this report.

Bee staff writer John Holland can be reached at 578-2385 or