Grape Moth Threatens Napa Valley Growing Method

When a voracious pest triggered a quarantine this week across much of Napa Valley — the nation's premier grape-growing region — it threatened more than the grapes themselves.

The spraying of pesticides needed to control the European grapevine moth threatens to undo decades of low-impact farming practices that have elevated the quality of wines from the region.

"That's a big concern for the growers," said Bruce Phillips, who grows 70 acres of cabernet sauvignon on the western slope of the valley.

Growers of premium wine grapes have long believed that elegant flavors are tied to the soil.

Phillips, the general manager of the Napa Valley Grape Growers Association, said the third invasive pest discovery in three years "raises the question of the long-term sustainability of organic and biodynamic practices."

Agriculture officials imposed a quarantine Tuesday restricting the transport of equipment, grapes and even the skins that are left when they are pressed after discovering the pest in at least 32 sites across Napa Valley.

The moth was first detected in the U.S. last September in a vineyard in the center of Napa Valley. The bug managed to destroy the crop of an entire vineyard at peak harvest time before anyone recognized the new invader.

"This is the worst of the invasive species, there's no question about that," said Jim Lincoln, who manages 400 acres of vineyards inside the 162-square-mile quarantine area. "It does real damage to the fruit, and it will be expensive to eradicate — if we can eradicate it."

The Beckstoffer Vineyards, which Lincoln manages, are not organic. But like most growers in the region, he tries to use minimal chemicals on the vines to protect the flavor of his grapes and the environment in which he and others work.

At an average $3,414 a ton for premium cabernet, damage can add up quickly in a county where the crop is worth $400 million annually. One acre can produce between three and four tons of quality grapes.