California table grape growers were concerned but not in panic mode in mid-May when the quarantine zone for the European grapevine moth expanded.

The state’s department of food and agriculture blamed warm weather for an increase in the number of the invasive pests that turned up in some of the more than 40,000 traps set up statewide.

The state established quarantine zones earlier this year in Napa, Sonoma and Solano counties after the moths were spotted in those areas. The state later expanded the zones in those counties and added portions of Fresno, Mendocino, Merced and Monterey counties to the list.

Of the counties that include quarantine zones, only Fresno County grows table grapes, said Barry Bedwell, president of the Fresno-based California Grape and Tree Fruit League. The other counties grow wine grapes.

Most of the state’s table grapes are produced in southern Tulare County and northern Kern County, about 80 miles from the nearest quarantine area, he said.

As of early June, about 1,100 square miles were under quarantine statewide, including 96 square miles in Fresno County.

Growers and those who harvest, transport or handle crops in the quarantine area will be asked to sign compliance agreements that dictate how crops, vehicles, equipment and related articles are to be treated while the quarantine is in effect, according to the CDFA.

Bedwell said he did not expect movement of grapes to be banned from the quarantine areas, and growers were waiting to see the compliance agreements that would spell out the protocol for moving table grapes.

It’s actually the larvae, not the adult moths, that damage the grapes, CDFA said. The damage increases from one generation to the next.

The good news is that the pest is relatively easy to control by treating the vines with conventional or organic products, Bedwell said.

As they geared up for the new table grape season, most growers were carefully monitoring their vineyards.

Any pest hosted by grapes is a concern to growers, said Jim Llano, sales manager for Castle Rock Vineyards, Delano, Calif.

But growers are particularly watchful for the European grapevine moth because it is a relative newcomer to the state, and growers are wary of it.

“We are vulnerable to this pest, but alert,” he said.

Tony Fazio, president of Fazio Marketing Inc., Fresno, Calif., said growers are working closely with CDFA, the U.S.

Department of Agriculture and industry trade organizations to make sure the pest does not travel outside the quarantine area.

“It’s easy to control this moth, but we want to make sure we continue to (follow) the right practices and make sure it doesn’t spread,” he said.