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Napa Vineyards Mandate Pressure Wash

Non-native pests are invading the valley, according to local grapegrowers who gathered to discuss their shared challenges this week.

Because land is dominated by vineyards, it makes it easier for pests to spread quickly from American Canyon to the Upvalley, growers said. And the two newest pests, the light-brown apple moth and European grapevine moth, seem to feel right at home in Napa County.

Growers, however, are not going to pull out vines and plant vegetables — a sure-fire way to chase out a grape-eating pest — because “the best use of the land is vineyards,” said Hal Huffsmith, Trinchero Family Estate’s vice president of vineyard operations.

Huffsmith was among the 125 people participants at a sustainability workshop put on by the Napa Valley Grapegrowers at Yountville Community Center Wednesday.

Huffsmith said both moths, which have been trapped as far north as St. Helena, are moving toward Calistoga. “So what can we do?” Huffsmith asked.

He said the industry needs to continue working with researchers, tap farmer wisdom — using trial and error with plantings, inspections, releasing natural enemies of the pests and more to see what works — and for growers to collaborate with their neighbors.

Huffsmith said one potential answer being discussed is a rootstock genetically modified to resist the pests. “But would you use (it)? That is a consumer-driven issue. But it is a possible solution.”

While growers fear the European grapevine moth could have devastating impacts on the winegrape industry, growers have learned to live with other pests who move more slowly or have less harmful effects on the fruit or life of the vines. Growers fear that the European moth will prove a more formidable foe.

“If we get one shot at defeating this (European grapevine moth), it is this spring,” Napa County Agricultural Commissioner Dave Whitmer said.

“This is the real deal. We need to take it seriously,” Whitmer said. “There is no single solution.”

“Right now,” he added, “We don’t know where it is and where it isn’t.”

The quarantine boundaries will expand if more moths are found. The strategy is to control the first and second generations of the European grapevine moth in a known quarantine area.

Whitmer said it appears the pest can be dealt with if its mating is disrupted. Whitmer said the federal and state Environmental Protection Agencies both approved the use of a mating disrupter. It should be available to growers by mid-April.

Growers will also be required to implement sanitation practices that will require pressure-washing everything from grape bins and vine trimmers to all machinery used in a quarantined vineyard . . .