Grape growers will pay about $2.50 more an acre to keep vine pests and disease from taking hold in Napa County vineyards.

The Napa County Board of Supervisors passed an increase in an assessment devoted to pest and disease prevention quietly Tuesday, a testament to most vineyard owners’ stance that the assessment is worth preventing the larger losses they could face from pests like the vine mealy bug.

The increase will bring the total assessment to $8.22 per acre, which means a total increase of anywhere from $2.62 to thousands of dollars, depending on the landowner. All growers with an acre or more must pay the assessment annually.

In fiscal year 2010/11, the assessment will garner $383,185, according to the Napa County Agricultural Commissioner’s office. It is part of a $1.07 million program that includes contributions from the California Department of Food and Agriculture and the county.

Grape growers barely blinked at the increase when considering the consequences of ignoring the pest threat.

“This is the economic engine of Napa County, and it’s important that we keep this economic engine healthy,” said Rex Stults, industry relations director for Napa Valley Vintners. 

Most of the increase will go toward a program geared at stopping mating of the Vine Mealybug, which feeds on vine leaves and infests their cones and fruit, said Dave Whitmer, Napa County Agricultural Commissioner. In high numbers, it hurts the yield and quality of the vines.

“We’re working with the industry to try to limit the spread of this pest so it doesn’t become an industry-wide problem,” Whitmer said.

The county is employing a new technology to keep the bugs from mating. Scientists have identified the pheromone that the female bugs, who don’t fly, use to attract mates, who do. 

Dispensers of the pheromones are placed in certain locations. The pheromones in the air confuse the male bugs in search of a mate. If they don’t find the females, they don’t mate, which ultimately reduces the population, Whitmer said.

“It’s a very kind of cutting-edge technology in that it’s reducing a pest population without having to spray any chemicals into the environment,” Whitmer said.

In Napa County, three areas have a population of the Vine Mealybug, including Orchard Avenue and Dry Creek Road, West Zinfandel Lane, and the north end of Big Ranch Road, he said. 

The assessment is a small price to pay compared to what is at stake if pests destroy a crop or the vines themselves, said Andy Beckstoffer, the owner of Beckstoffer Vineyards.

Grape growers want to address the problem, and they hope to do it in a way that isn’t harmful to the environment, he said. Often that is more expensive.

“It seems like in the 40 years I’ve been here we have a bug of the month,” he said. “Every time I turn around, there’s another bug, and they’re devastating bugs.”

The Napa County Winegrape Pest and Disease Control District began in 2002 to fight the Glass-Winged Sharpshooter and Pierce’s Disease in Napa County.

Pierce’s Disease is a bacterial infection that is fatal to vines, and the sharpshooter carries it.

In 2002, grape growers overwhelmingly approved an assessment of up to $20 an acre per year. In 2006, they voted to expand the program to include other pests and diseases.

The program has been successful in keeping Glassywinged sharpshooters out of the county, said Sandy Elles, director of the Napa County Farm Bureau.

All incoming nursery products are inspected through the program, and some shipments have been turned back when the bugs are found, she said.

Beckstoffer said it is the vineyard owners’ responsibility to take a role in the fight, rather than pass it to the government. He has 1,053 acres in Napa County, according to the Vineyard’s website. The assessment will be significant with the increase —  $8,655.66 annually.

“It will be substantial, but it’s worth it,” he said. “We can’t afford not to do this."