NAPA, Calif. -- "Not in my backyard!" is the bold-faced cry of the sign posted beside the Napa highway.

The interloper in question, though, isn't a hulking new development or stinky chemical plant. It's a little brown bug called the glassy-winged sharpshooter that can take down mighty vineyards with deadly precision.

The NIMBY campaign enlisting Napa County residents as vector vigilantes is part of California vintners' war with the sharpshooter, which spreads a fatal vine affliction known as Pierce's disease.

This month, grape growers are being asked to continue the defense by extending a special assessment that raises money for research on the bug and the disease it carries.

"Once the pest becomes established -- you've already lost the game," said Central Valley grower Steve Schafer, who is voting yes. "We have to contain it and try to eradicate it."

Pierce's disease has been around for decades, caused by bacteria that flourish along waterways. But in the past, damage was limited because the bacteria was carried by insects that couldn't go very far. The trouble with the glassy-winged sharpshooter, which showed up in California about 15 years ago, is that it can soar for up to a quarter-mile.

In the late 1990s, the disease ravaged Southern California vineyards, causing an estimated $40 million in losses in Riverside County's Temecula area.

So far, Napa and adjoining Sonoma counties are sharpshooter-free, but a few sharpshooter egg clusters have been found on nursery shipments from Southern California, raising alarm.

The assessment election being conducted by mail-in ballot this month asks grape growers to extend until 2011 a tax set at a maximum of $3 per $1,000 worth of grapes sold.

There is no formal opposition to the measure, and backers believe the assessment will pass.

Supporters point out that the tax, set to expire in 2006 unless the election is successful, has already raised $17 million that, along with matching grants, has been leveraged into millions more through matching funds for research.

Among the projects is an attempt to turn grapes into warriors by developing fruit with resistance to Pierce's disease.

Wild grapes already exist that can fight off the disease; unfortunately they aren't too tasty. University of California, Davis, viticulture professor Andrew Walker is using traditional crossbreeding techniques to try to come up with a disease-resistant grape that tastes good.

Researchers say the fruit quality has improved significantly in two generations and the plants remain highly resistant to Pierce's disease.

Walker and his lab are also developing molecular maps that are providing DNA markers to accelerate breeding and help locate the resistance genes in wild grapes. The eventual goal is to insert the genes into classic wine grape varieties.

That is a far more controversial area of research, although Walker notes it is grape-to-grape as opposed to inserting DNA from a nonrelated species.

Genetically engineered grapes are at least a decade away and aren't likely to be used in wine unless public attitudes change. For now, it seems unlikely they'd be embraced by detail-obsessed wine connoisseurs who want to know precisely where the grapes in their bottle originated.

Still, biotech opponents are concerned about what may happen.

In the key wine-producing region of Sonoma County, adjacent to Napa Valley, voters are expected to decide this November whether to become the fourth California county to ban genetically modified organisms.

The measure would prohibit the cultivation of genetically altered plants and animals for 10 years. It excepts agricultural or medical research conducted in labs with a high biosecurity rating. There is also a clause allowing county supervisors to amend the measure by unanimous vote.

Dan Solnit, campaign coordinator for GE-Free Sonoma County, said the measure gives the county time to gauge the effects of genetically engineered crops. "Until we know what we're dealing with, we should not be putting it out in the fields."

Opponents see the measure as too restrictive.

Nick Frey, executive director of the Sonoma County Grapegrowers Association, said a lot would have to change before the tradition-bound wine industry starts using genetically engineered grapes. But he thinks it can provide relief for problems like Pierce's disease -- and that's research that needs to be done in the field.

"I'm a firm believer that understanding basic biology will have value," he said.

Meanwhile, the sharpshooter remains insect non grata in wine country.

In Napa, county Agricultural Commissioner Dave Whitmer said the NIMBY campaign, which includes TV spots showing a giant sharpshooter trying to hitch a ride with an unsuspecting couple, was chosen as a way to get people engaged in finding and reporting the pest.

"My role is to try and keep the glassy winged sharpshooter out of Napa County long enough for there to be a solution to Pierce's disease," he said. "Keeping it out is far better than having to deal with it."