Inspectors reported finding two Asian citrus psyllids in residential parts of Manteca and Lodi.
It is believed to be the first detection in the northern San Joaquin Valley of the pest, which has done heavy damage to Florida growers and is a danger as well to California citrus, mainly in the South Valley.
The psyllids were found in traps near North Main Street and East North Street in Manteca and near Chestnut and Church streets in Lodi, said Tim Pelican, agricultural commissioner for San Joaquin County. Each location is in an established neighborhood in the central part of each city. Pesticide spraying was planned for citrus trees in the affected areas, along with increased monitoring.
Psyllids can carry a disease called huanglongbing, also known as citrus greening. Infected trees yield bitter, misshapen fruit and eventually die. There is no cure.
The pest has done about $1.3 billion in damage to Florida groves in recent years. Last month, the state Department of Agriculture has expanded a citrus quarantine to encompass all of Tulare County after the latest psyllid discovery there, two of the tiny pests in the city of Tulare. The first psyllid finding in Tulare County happened in 2012.
Tulare County has more than 118,000 acres planted to citrus trees, according to the county agricultural commissioner's office, and production of citrus crops accounted for more than $1 billion in value in 2013. Nursery stock for citrus and subtropical trees represented another $11 million in value.
Tulare County is the only San Joaquin Valley county that is under a countywide quarantine for the Asian citrus psyllid.
Quarantines are in place in portions of Fresno and Kern counties. Elsewhere in the state, all of Imperial, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara and Ventura counties are under quarantine, as well as part of San Luis Obispo County.
While the psyllid has been detected in those counties, the only instance of citrus greening was at a home in Los Angeles County in 2012, according to the state Department of Food and Agriculture.
The north Valley has plenty of backyard orange, grapefruit and lemon trees, but commercial production is minor compared with the region's peaches, cherries, apricots and apples. San Joaquin County, for instance, lumped citrus in with its 800 acres of miscellaneous fruit. Despite that, the pest can be transmitted via fruit boxes, nursery shipments and other means.