Moth 'can be fought effectively'

Leaders say they can eradicate European grapevine moth

By WES SANDER

Capital Press

California county agriculture commissioners are optimistic about the prospects of getting rid of the European grapevine moth.

"Basically, we're going to have to eradicate the pest," said Tye Hafner, Fresno County's deputy agricultural commissioner for Fresno County.

The infestation "is very low-level, so we are very confident that we will achieve eradication," Hafner said.

Since the moth was first noticed last year in the coastal vineyards of Northern California, traps have revealed the moth up and down the San Joaquin Valley, where orchards and vineyards have expanded in the past decade.

The first federal quarantine appeared in March in Napa County, and new quarantines soon followed to the north and inland in Fresno and Merced counties. Thirteen counties now have quarantines for the moth.

Success in controlling the moth in Napa County is giving cause for optimism, with the total number of trapped moths falling from roughly 100,000 in the spring to about 1,300 by mid-summer, deputy agricultural commissioner Greg Clark said.

"It just shows that this pest can be fought effectively," Clark said. "We're optimistic that we will continue to see the same progress."

"It may well be there are no other additional counties that are quarantined, but only time will tell," Clark said.

In Napa, the greatest impact has been the cost of treating vineyards, Clark said. Most grapes stay within the area for crushing into wine, so outside markets don't play a major role in the region's industry.

Each county has specific rules for moving particular crops, but protocols largely follow the interstate-movement rules written by USDA's Animal and Plant Health Inspection Service.

Federal quarantines are triggered when routine trapping turns up two invasive insects in the same area. USDA's Animal and Plant Health Inspection Service first sets rules by which farm goods from within a quarantine can cross state lines.

The state then sets movement restrictions based on those rules, applying them not only to shipment across quarantine boundaries, but also between properties within a quarantined area. County agricultural commissioners handle the details of compliance.

The moth's impact to yields starts with the first-generation larvae, which feed on flowers. Second-generation larvae feed on grape clusters before pupating inside the fruit. The third generation causes the most damage, feeding on ripening grapes and causing fungal damage and rotting.

It feeds on other crops, but does most of its damage to grapes. It is found in southern Asia, Europe, North Africa, Anatolia, the Caucasus and South America.

The state is conducting mandatory treatments for backyard grapevines. But for commercial vineyards, treatments are voluntary. Strategies generally involves spraying four times annually, targeting each new generations as it hatches.

In order to move grapes to handlers or winemakers outside quarantine boundaries, a producer must have a "compliance agreement," certifying a producer has taken the required precautions.

"We hope next year that it's not as widely distributed," said Clark of Napa County. "Hopefully growers have been able to eliminate the moth in their area, so we can start to focus on smaller areas."

"It's important also for people to note that this isn't the end of the battle," he said. "This same kind of diligence is going to be needed next year."