Asian Citrus Psyllid Detection In Santa Clara County Expands Quarantine Into Alameda County

Taylor Hillman Citrus

Adult Asian citrus psyllid, Diaphorina citri Kuwayama. Photograph by Douglas L. Caldwell, University of Florida.

Adult Asian citrus psyllid, Diaphorina citri Kuwayama. Photograph by Douglas L. Caldwell, University of Florida.

Following the detection of an Asian citrus psyllid (ACP) within the City of San Jose, the existing quarantine has been expanded to include an additional portion of northwest Santa Clara County and a portion of southern Alameda County along its border with Santa Clara County.

The quarantine expansion in Santa Clara County adds 4 square miles to the northwest of the current quarantine and the new quarantine expansion into Alameda County measures approximately 9 square miles in the Fremont area.

The quarantine area in Alameda County is bordered on the north by Warren Avenue and Agua Fria Creek; on the south and east by the Santa Clara County Boundary Line; and on the west by Union Pacific Railroad. The quarantine maps for both Santa Clara and Alameda Counties are available online at:

The quarantine prohibits the movement of citrus and curry leaf tree nursery stock, including all plant parts except fruit, out of the quarantine area and requires that all citrus fruit be cleaned of leaves and stems prior to moving out of the quarantine area. An exception may be made for nursery stock and budwood grown in USDA-approved structures which are designed to keep ACP and other insects out. Residents with backyard citrus trees in the quarantine area are asked not to transport or send citrus fruit or leaves, potted citrus trees, or curry leaves from the quarantine area.

In addition to quarantines in portions of Santa Clara, Alameda, Fresno, Kern, Madera, San Benito, San Joaquin, and San Luis Obispo; ACP county-wide quarantines are now in place in Imperial, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, Tulare and Ventura counties.

The ACP is an invasive species of grave concern because it can carry the disease huanglongbing (HLB), also known as citrus greening. All citrus and closely related species, such as curry leaf trees, are susceptible hosts for both the insect and disease. There is no cure once the tree becomes infected, the diseased tree will decline in health and produce bitter, misshaped fruit until it dies. HLB has been detected just once in California – in 2012 on a single residential property in Hacienda Heights, Los Angeles County. This plant disease does not affect human health.

Residents in the area who think they may have seen ACP or symptoms of HLB on their trees are urged to call CDFA’s Pest Hotline at 1-800-491-1899 or your local agricultural commissioner’s office (Alameda County (510) 670-5232; Santa Clara County (408) 918-4600. For more information on the ACP and HLB, please