09/11/2025 | News release | Distributed by Public on 09/11/2025 12:40
The California Department of Food and Agriculture declared a new citrus quarantine in northern San Diego County and part of Marine Corps Base Camp Pendleton Sept. 9.
State officials declared the quarantine after finding Huanglongbing, a bacterial disease that is fatal to citrus trees, in one citrus tree in a residential neighborhood in the San Clemente area during regular inspections. Huanglongbing (HLB) is also known as citrus greening.
The new quarantine area will be San Diego's first multi-jurisdictional quarantine. It will span from southern Orange County to northern San Diego County, in the San Onofre and Agra areas, including the northwest part of Camp Pendleton. Existing quarantines in Fallbrook, Oceanside, Rancho Bernardo and Valley Center are ongoing. The maps for this HLB quarantine are available here.
This bacterial disease is a major threat to San Diego County's $144 million annual citrus crop and can impact residential citrus tree owners. HLB causes misshapen, bitter fruit and eventually kills infected trees. No businesses are expected to be affected by the new quarantine, including over growers of commercial citrus, nurseries and markets.
The intent of the quarantine is to protect the region's food supply, agricultural economy, and environmental sustainability by restricting people and businesses from moving citrus nursery stock, plant parts, and fruit outside the quarantine boundaries and off their properties. The only exception is for agricultural businesses that must adhere to specific requirements for treatment, cleaning, and packing commercial fruit prior to movement.
The disease is not harmful to people or animals but is deadly to citrus and could be devastating to the county's citrus industry. HLB is spread by tiny insects, the Asian citrus psyllid, if they are carrying the bacterium when they feed on citrus trees. Samples from trees on the property where HLB was confirmed-as well as the surrounding area-are undergoing tests for the disease.
"Unfortunately, Huanglongbing is fatal to citrus, so our goal is to prevent this disease from spreading," said San Diego Agricultural Commissioner Ha Dang. "By working together, we can all protect our food supply, local agriculture, and environment from this devastating disease. Partnering with state and federal regulatory partners, we are working closely with residents and agricultural operators and ask for everyone's cooperation with the ongoing regulatory activities."
The California Department of Food and Agriculture will work with residents in the immediate area to arrange for treatment of citrus trees as a protective measure against the disease.
County officials are also proactively notifying local citrus growers, plant nurseries, and other related businesses. If the disease is detected in additional citrus trees in the quarantine area, CDFA officials will contact properties regarding treatment and removal of the infected trees. Nearby trees will be treated, and regulatory survey efforts will be increased to prevent the spread of the disease in the area.
Infected trees may have areas with mottled yellow leaves, generally seen in asymmetrical patterns and bear small, asymmetrical fruit, which is partially green, bitter, and not fit for sale or eating. The disease destroys the appearance and economic value of the trees and eventually causes their death, typically within a few years.
Inside the quarantine area, the County urges residents to take the following steps: