Citrus quarantine declared in North County after deadly disease found

SAN DIEGO (FOX 5/KUSI) -- California agricultural officials have declared a new citrus quarantine in northern San Diego County, extending into part of Marine Corps Base Camp Pendleton, after a deadly citrus tree disease was detected in the region.

Officials with the California Department of Food and Agriculture (CDFA) announced the quarantine on Monday, Sept. 9, after confirming the presence of Huanglongbing (HLB), commonly known as citrus greening, in a residential citrus tree in the San Clemente and Agra areas during routine inspections.

The disease poses a major threat to San Diego County’s $144 million citrus industry. While not harmful to humans or animals, HLB is fatal to citrus trees—causing misshapen, bitter fruit and eventually killing the tree.

HLB is spread by a tiny insect called the Asian citrus psyllid. When infected psyllids feed on citrus trees, they can transmit the bacterium that causes the disease.

Infected trees often show signs such as yellow, mottled leaves in irregular patterns and small, bitter, misshapen fruit. The disease eventually kills the tree, usually within a few years.

According to county officials, the newly declared quarantine area is San Diego’s first to cross jurisdictional boundaries, stretching from southern Orange County to northern San Diego County. It includes the San Onofre and Agra areas, along with the northwest portion of Camp Pendleton.

This new quarantine joins existing restrictions already in place in Fallbrook, Oceanside, Rancho Bernardo, and Valley Center.

Residents and businesses within the quarantine zone are now required to follow strict guidelines. Moving citrus plants, cuttings, or fruit outside of the area is prohibited—except for commercial growers who meet strict treatment and handling standards.

Officials stress that local businesses, including nurseries and citrus markets, are not expected to be negatively impacted under the current order.

County officials are urging residents in the affected areas to take the following actions:

• Do not move citrus plants or fruit in or out of the quarantine zone.
• Thoroughly wash backyard citrus and remove stems and leaves before moving it from the property.
• Double-bag and dry out clippings before disposal.
• Cooperate with agricultural inspectors conducting tree inspections and treatments.
• Only purchase citrus trees from reputable, local nurseries.
• Report any sick or dying citrus trees by calling CDFA’s Pest Hotline at (800) 491-1899.

If a resident no longer wants to care for their citrus tree, officials recommend contacting a tree removal service to help prevent it from becoming a host to the disease.

For more information, visit CaliforniaCitrusThreat.org or contact the San Diego Department of Agriculture, Weights and Measures at 760-752-4700.