California wine country says goodbye to crop-threatening moth

A moth that sparked quarantines and expensive pest-control measures in California’s wine country has been eradicated from the state, agricultural officials said Thursday.

Little-known outside the viticultural world, the European grapevine moth had threatened crops valued at $5.7 billion, including wine and table grapes, berries and some stone fruits, since it first was detected in Napa County in 2009. The discovery sparked a quarantine that eventually spanned more than 2,000 square miles in 10 counties and briefly halted exports of some fruit.

But an intensive program of trapping and spraying of a naturally occurring bacteria eliminated the infestation, according to the California Department of Food and Agriculture.

Known by the scientific name Lobesia botrana, the grapevine moth originated in southern Europe before spreading to northern Africa, the Middle East, Asia, and South and North America. It infests grape crops, although it has been found in berries, stone fruit and pomegranates. The moth’s several larval stages damage flowers and the fruit itself throughout the growing season, often leaving grapes vulnerable to fungi or other pests, according to the UC’s Division of Agriculture and Natural Resources.

“It is no easy feat to eradicate an invasive species, especially one like the European grapevine moth when it gains a foothold in a place as hospitable as California’s prime wine-grape growing region,” said state Agriculture Secretary Karen Ross, who credited a coordinated state, federal and private campaign against the pest.

Growers were encouraged to remove infested fruit, set traps laced with moth-attracting pheromones and treat crops with Bacillus thuringiensis, a natural bacterium that produces proteins toxic to many insects. Within a year, detection of the insect dropped from 100,000 to about 144, and by 2014, no insects were found in traps. Several years without any sign of them led agricultural officials to declare the pest eradicated.

State Food and Agriculture officials did not estimate the cost of the campaign, but agriculture officials in Napa County have reported that grape growers spent $45 million to deal with the moth, while government agencies spent a similar amount.

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