Detection of Huanglongbing Triggers Quarantine Expansion in San Bernardino and Riverside Counties


A quarantine expansion has been declared following the detection of the citrus disease Huanglongbing (HLB), or citrus greening, in two residential citrus trees in Colton. This is the first time the disease has been confirmed in Colton, and the detection came on the heels of the first detection in San Bernardino County in November 2019. The California Department of Food and Agriculture (CDFA) is working with the United States Department of Agriculture (USDA) and the San Bernardino County and Riverside County agricultural commissioners on this project.

The expanded 51 square mile quarantine area will link up with the existing quarantines in San Bernardino and Riverside Counties, putting more than 1,275-square miles of Southern California into the HLB quarantine area. The expanded portion is bordered on the north by West Fifth Street and East Fifth Street; on the east side of Highway 210 near Redlands by West Highland Avenue and San Timoteo Canyon Road in San Bernardino County; and on the south by Pico Visto Way in Riverside County.

HLB quarantine maps for San Bernardino and Riverside counties are available online at: Please check this link for future quarantine expansions in these counties, should they occur.

The quarantine prohibits the movement of all citrus nursery stock or plant parts out of the quarantine area. Provisions exist to allow the movement of commercially cleaned and packed citrus fruit. If you are a grower within the new quarantine expansion area, please contact CDFA’s emergency quarantine response program at 916-654-0312 for information on these provisions.

Fruit that is not commercially cleaned and packed, including residential citrus, such as oranges, lemons, grapefruits, and kumquats, must not be moved from the property on which it is grown, although it may be processed and/or consumed on the premises.

Residents are urged to take several steps to help protect citrus trees:

  • Do not move citrus plants, leaves, or foliage into or out of the quarantine area or across state or international borders. Keep it local.
  • Cooperate with agricultural officials placing traps, inspecting trees, and treating for the pest.
  • If you no longer wish to care for your citrus tree, consider removing it so it does not become a host to the pest and disease.

HLB is a bacterial disease that affects the vascular system of citrus trees and plants. It does not pose a threat to humans or animals. The Asian citrus psyllid can spread the bacteria as the pest feeds on citrus trees and plants. Once a tree is infected, there is no cure; the tree will produce bitter and misshaped fruit and die within a few years.

CDFA staff have scheduled removal of the infected trees and are in the midst of a treatment program for citrus trees to knock down Asian citrus psyllid infestations within 400 meters of the find site. By taking this action, a critical reservoir of the disease and its vectors will be removed, which is essential to protect surrounding citrus from this deadly disease.

Growers in San Bernardino County and Riverside County near the expanded quarantine area are invited to the San Bernardino County Grower Meeting, located at the Redlands City Hall Council Chambers on Feb. 3 at 10 a.m. At the meeting, attendees can ask questions and hear the latest on the mandatory protocols for growers in an HLB quarantine area.

CDFA, in partnership with the USDA, local county agricultural commissioners, and the citrus industry, continues to pursue a strategy of controlling the spread of the Asian citrus psyllids while researchers work to find a cure for the disease.

If you are a citrus grower in San Bernardino County and have questions about this detection, please contact your grower liaison Sandra Zwaal at

If you are a citrus grower in Riverside County and have questions about this detection, please contact your grower liaison Alan Washburn at

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