Federal and state agriculture officials are expanding quarantines in Southern California following new detections of citrus greening, the devastating disease also known as Huanglongbing (HLB).
The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS), working with the California Department of Food and Agriculture (CDFA), announced that the quarantine boundaries in Riverside and Orange Counties are being widened to prevent further spread.
Citrus greening is one of the most destructive citrus diseases worldwide. Caused by the bacterium Candidatus Liberibacter asiaticus, the disease is spread by the Asian citrus psyllid and has no cure. Once a tree becomes infected, it typically dies within a few years. Although the disease does not pose a health threat to people or animals, it has wiped out millions of acres of citrus production across the United States and in other citrus-producing regions around the globe.
In the United States, citrus greening is established in Georgia, Florida, Puerto Rico and the U.S. Virgin Islands, and it is present in portions of Alabama, California, Louisiana, South Carolina and Texas. Infected trees produce fruit that never fully ripens, often appears misshapen or lopsided, and tastes bitter. Because of the quality loss, this fruit can only be used for juicing, leading to severe economic impacts for growers.
At the beginning of this year, APHIS noted it is expanding the quarantined area in the Corona region of Riverside County by 37 square miles and enlarging the quarantine around San Juan Capistrano in Orange County by 18 square miles. These actions mirror intrastate quarantines set by CDFA on December 5 and 15, 2025, after plant tissue samples collected from residential properties in both counties tested positive for the disease.
The expansion affects commercial production areas in both regions. According to APHIS, 26.5 acres of commercial citrus fall within the new quarantine boundaries in the Corona area, while approximately 267 acres are impacted in the San Juan Capistrano expansion zone.
Under federal regulations, safeguarding measures outlined in 7 CFR 301.76 and related Federal Orders will govern the interstate movement of regulated citrus materials from these quarantined zones.
Officials say the move is necessary to protect citrus-growing regions elsewhere in the country from the disease’s further spread. Once HLB becomes established, it is extremely difficult—if not impossible—to eradicate, leaving prevention and early detection as the industry’s strongest defenses.
The Asian citrus psyllid, the tiny insect responsible for transmitting the bacterium, is a key focus of monitoring and control efforts. APHIS notes that psyllid eggs are yellow-orange and almond-shaped, typically tucked into crevices or leaf folds. Nymphs are difficult to see with the naked eye but can be identified by the waxy, white excretions they leave on plants. Adult psyllids are about 1/8 of an inch long and tend to jump or fly when disturbed. Their abdomens may appear blue-green, gray-brown, or orange-yellow, and the insects have mottled brown wings and antennae with black tips on the last two segments.
Trees infected with citrus greening may initially show no symptoms, making them silent carriers capable of spreading the bacterium to nearby plants. As the disease progresses, fruit production declines and remaining fruit may be partially green, small, irregularly shaped, and bitter. Leaves often develop blotchy, asymmetrical yellow mottling and trees may experience twig dieback and premature fruit drop.
With citrus production remaining a vital part of California agriculture, officials emphasize the importance of public awareness, early reporting and compliance with quarantine rules.
More information on citrus greening and the Asian citrus psyllid is available from APHIS at https://www.aphis.usda.gov/plant-pests-diseases/citrus-diseases/citrus-greening-and-asian-citrus-psyllid.
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About the Author
Keith Loria
A graduate of the University of Miami, Keith Loria is a D.C.-based award-winning journalist who has been writing for major publications for more than 20 years on topics as diverse as healthcare, travel, sports and produce.
