Asian citrus psyllids are found in larger numbers in the San Joaquin Valley (SJV) of California. This time in considerable numbers in the city of Bakersfield and now in the Stanislaus County city of Turlock.

The latest finds mark the first discoveries of the invasive pest in Stanislaus County, according to Milton O’Haire, county agricultural commissioner.

The Stanislaus County find follows discoveries in neighboring San Joaquin County a year ago. Those followed earlier finds of a breeding population in San Jose.

The Turlock discoveries were confirmed on yellow sticky traps used by the California Department of Food and Agriculture (CDFA). No live psyllids have been discovered at this point, O’Haire says.

Sampling protocols are different than in other portions of the SJV, he says.

Sticky traps are being placed on trees within nine miles of the initial find and are being saturated throughout the region as inspector’s canvas neighborhoods looking for citrus plants. The ACP is only known to feed on and infect citrus with a fatal bacterial disease called Huanglongbing (HLB), or citrus greening disease.

O’Haire says the process is being slowed by canvassing the neighborhood to inspect yards for citrus trees.

Treatment of citrus plants will take place within 400 meters of the initial find, not the 800 meters common in other regions of the state. A quarantine zone is being prepared to encompass a five-mile radius of the discovery. Traps will be placed out to a radius of nine miles.

While the nearest commercial citrus is a considerable distance away in the western portion of the county, O’Haire says two large commercial nurseries in neighboring cities and perhaps two more that could be built in the county may be impacted by quarantines as they are established.

O’Haire says the two large nurseries are already screened and employ protocols to keep out the ACP, which can vector HLB by feeding on citrus.

Stanislaus County agricultural officials are increasing their inspections of flea markets, farmers markets and other venues where citrus is commonly sold to ensure quarantine regulations are met and that the pest is not present in trees or on plant material.

“Our biggest concern right now is home-grown citrus,” O’Haire said.

Quick growth in Bakersfield

Kern County Agricultural Commissioner Ruben Arroyo reports multiple pest finds in the county – predominantly within the city of Bakersfield, including a breeding population discovered in a west Bakersfield neighborhood.

Arroyo says inspectors are finding new psyllids “almost daily” in the region. The area is at the south end of the SJV and includes one of the larger commercial citrus growing regions in the state.

Because of the large number of finds, Arroyo says his staff is assisting the CDFA in trap inspections and searches for the pest.

Kern County is home to over 64,000 acres of commercial citrus, which generally skirts Bakersfield on the east and south.

At least one discovery was made in commercial citrus near Arvin, south of Bakersfield, Arroyo said.

The discoveries on the east side of the city will likely place some of the county’s commercial citrus within a quarantine zone. The citrus is generally located east of Weedpatch Highway to the General Beale Road area and south of Hwy. 58 to as far south as Herring Road, based on a map provided by Arroyo.

Commercial groves east of Hwy. 99 between about David Road on the north to the edge of the foothills south of Arvin and Lamont are already within an ACP quarantine, according to the same map.

Because not all of Kern County is currently under an ACP quarantine, certain regulatory procedures are in place to restrict how citrus is moved between southern California, where the pest is well-established, and the San Joaquin Valley.

Tulare County, which neighbors Kern County to the north, is the northernmost county in the state with a countywide ACP quarantine. Tulare and Kern counties produce much of the state’s fresh citrus. Combined nearly 200,000 acres of commercial citrus is grown in the two counties.

Parts of California’s Central Coast also have populations of the ACP. To date the only discoveries of HLB, or citrus greening disease, found in California continues to be in the San Gabriel Valley region of Los Angeles County. Nine trees have been confirmed positive for the disease since 2012, with most of those discoveries happening this summer.

Those trees were removed by the CDFA in an attempt to slow the spread of HLB.

For the latest on western agriculture, please check out Western Farm Press Daily and receive the latest news right to your inbox.