(Aug. 26) TULARE, Calif. — Although strides have been made in the fight against the glassy-winged sharpshooter — blamed for spreading Pierce’s disease in vineyards — the pest has now taken up residence in citrus trees.

Kevin Andrew, senior vice president of operations for Sun World International Inc., Bakersfield, Calif., said the pest does not cause Pierce’s disease in citrus, but sucks juice out of fruit, which can reduce the size of oranges and other kinds of citrus.

Andrew is chairman of California Gov. Gray Davis’ Pierce’s disease task force.

Speaking to members of the National Agri-Marketing Association Central California Chapter California Ag 2002 meeting Aug. 20, Andrew said the glassy-winged sharpshooter loves citrus.

SPREADING

Despite efforts to prevent spread of the insect from Kern County north to Tulare County, glassy-winged sharpshooters have moved north through citrus groves to the Tulare area.

“We have found as many as 6,000 bugs in each tree,” Andrew said. “The sharpshooter has an avenue through citrus. They can spread up and down the valley.”

A pilot program to fight the spread of glassy-winged sharpshooters and Pierce’s disease is in operation in Kern County. The program includes a buffer zone to help prevent spread of the pest.

The Pierce’s disease task force has approached citrus growers about spraying their trees to reduce glassy-winged sharpshooter numbers.

Only a few citrus groves have been hurt by the pest so far, he said.

Besides its love for grapevines and citrus, the pest has been found in red and green pepper plants.

“It is the most adaptable bug we’ve ever worked with,” Andrew said.

Consequently, every effort must be made by the California Department of Food and Agriculture and the U.S. Department of Agriculture to fund and fight the pest and Pierce’s disease, Andrew said.

So far, a number of strategies are being tried including removing infected grapevines, treating plants through their roots with Admire insecticide, and with the release of 181,000 tiny wasps that feed on glassy-winged sharpshooter larvae.

Scientists are taking aim at Kern County and its vast table grape crop in the fight against Pierce’s disease. The fight also continues in Temecula, Calif., where the disease is estimated to have ruined 40% of the wine grape crop.

ISOLATED SO FAR

Scientists have confirmed that Pierce’s disease exists in a dozen vineyards east of Bakersfield, including the farm town of Arvin. So far, damage has been isolated and the problem has not been found in the rich grape-growing region of Delano.

But the threat is there, and a coordinated effort has begun to monitor glassy-winged sharpshooter populations in Kern County while finding ways to combat the pest. The Kern County Agricultural Commissioner’s Office, the CDFA and the USDA are participating in the Kern County Pilot Project.

The project area covers about 13,000 acres of crop land that is heavily infested with the glassy-winged sharpshooter. Two popular table grape varieties — flame seedless and red globe — are most threatened by Pierce’s disease.

Researchers have started work on about 60 projects to find ways to prevent the disease.

Statewide the estimated damage from Pierce’s disease stands at about $12 million.