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News Release

California Department of Food and Agriculture

Media Contacts: CDFA Public Affairs, (916) 654-0462,

California Department of Food and Agriculture
Release #19-135
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SACRAMENTO, December 20, 2019 - A quarantine has been declared following the detection of the citrus disease Huanglongbing (HLB), or citrus greening, in multiple residential citrus trees within the City of Corona, Riverside County.  The United States Department of Agriculture (USDA), the Riverside County, Orange County, and San Bernardino County agricultural commissioners, and the California Department of Food and Agriculture (CDFA) are working collaboratively on this project.

The 107-square mile quarantine area will link up with the east side of the existing quarantine in Los Angeles, Riverside, Orange, and San Bernardino counties, creating a contiguous 1,127-square-mile area. The new portion is bordered on the north by Chino Airport, on the south by Black Star Canyon, and on the east by Interstate 15.  HLB quarantine maps are available online at:  Please check this link for future quarantine expansions in these counties, should they occur.  Quarantines are already in place for HLB in portions of Los Angeles, Orange, Riverside, and San Bernardino counties. 

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.  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 the 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 other plants.  Once a tree is infected, there is no cure, the tree will produce bitter and misshaped fruit and dies 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 eliminate 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 the surrounding citrus from this deadly disease.

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. 


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California Department of Food and Agriculture Office of Public Affairs
1220 N St., Ste. 214, Sacramento, CA 95814