The California Department of Food and Agriculture has declared a new citrus quarantine in Fallbrook after detecting the citrus tree disease known as Huanglongbing — or citrus greening — in one mandarin tree in a residential neighborhood. The tree-killing bacterial disease, which was detected by the state during a routine inspection, is a major threat to the region’s $138 million annual citrus crop and can impact residential citrus tree owners, according to county officials. HLB causes misshapen, bitter fruit and eventually kills infected trees. There are more than 450 businesses that may be affected within the quarantine, which includes more than 100 growers with approximately 830 acres of commercial citrus, four nurseries and a farmer’s market in downtown Fallbrook that may have citrus trees. “Unfortunately, Huanglongbing is fatal to citrus, so our goal is to prevent this disease from spreading,” said San Diego County Agricultural Commissioner Ha Dang. “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.” HLB quarantines already exist in the city of Oceanside, Valley Center and the neighborhood of Rancho Bernardo. The new area covers the area bordered on the north by De Luz, to the south by Interstate 76 and Camino Del Rey, to the west by Camp Pendleton and to the east by Interstate 15. The only exception to the quarantine 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. HLB is spread by tiny insects, called Asian citrus psyllid, if they are carrying the bacterium when they feed on citrus trees. State officials will be working with residents in the immediate area to arrange for treatment of citrus trees as a protective measure. County officials are also notifying local citrus growers, plant nurseries and other businesses. Samples from trees on the property where HLB was confirmed and nearby are being tested for the disease. Infected trees may have areas with mottled yellow leaves, generally seen in asymmetrical patterns, and bear small, asymmetrical fruit that are partially green, bitter and not fit for sale or eating, according to county officials. Officials urge residents in the quarantine area not to move citrus plants, leaves or foliage into or out of the area. They should dry or double-bag plant clippings prior to disposal, remove all leaves and stems and thoroughly wash citrus. They should contact a tree removal service if they no longer wish to care for a citrus tree, and they should only buy citrus trees from reputable local nurseries. Anyone can report citrus trees that seem to be sick or dying by contacting the state’s toll-free pest hotline at (800) 491-1899 or visiting cdfa.ca.gov/plant/acp. For questions about moving commercial citrus and HLB quarantine regulations, contact the county agriculture department at (760) 752-4700 or visit sdcawm.org.