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Posted 11 August 2008. PMN Crop News.

Information Available on Asian Citrus Psyllid Discovered in Tijuana

Syngenta Crop Protection.

Davis, California (June 30, 2008)--Efforts have been ramped up on the California-Mexico border to keep out a citrus pest known as the Asian citrus psyllid. The insect was trapped in Tijuana, less than two miles from the California border. The psyllid can carry a bacterial disease called citrus greening, which renders the fruit bitter tasting and can kill citrus trees. Neither the disease nor the insect has been found in California.


Extensive surveys of citrus in California are being conducted by the California Department of Food and Agriculture near the border, and so far the pest has not been found on the California side.

The pest is originally from Asia. Previously, this pest had been known to be established in central Mexico, the Caribbean islands, and throughout Florida since its introduction there in 1998. More recent psyllid infestations include Texas since 2001, Hawaii in 2007 and coastal Louisiana in May 2008.

The psyllid is an efficient carrier of the bacterium that causes the disease called Huanglongbing (HLB) or citrus greening because the fruit does not color properly. Symptoms of HLB include yellow shoots and mottling and yellowing of leaves due to lack of the green pigment chlorophyll. Infected trees are stunted, sparsely foliated, and may bloom off-season. In addition, there is twig dieback, leaf and fruit drop, production of small, lopsided, hard fruit, and small, dark aborted seeds. There is no cure for HLB, and diseased trees must be removed as quickly as possible to prevent spread of the disease.

In 2006, entomologist Beth Grafton-Cardwell from University of California (UC) Riverside organized a team of researchers from the University of Florida and California Department of Food and Agriculture to develop a brochure, Web site, and slide presentation to educate California citrus growers, the ornamental nursery industry, and regulatory agency staff about Asian citrus psyllid and greening disease. The University of California Exotic/Invasive Pests and Diseases Research Program funded the project.

"The Asian citrus psyllid was first discovered in Florida in 1998 and in three years, the psyllid was found statewide," said Grafton-Cardwell. "The psyllid infests certain ornamentals such as orange jasmine (Murray paniculata) and in Florida was spread by distribution of those plants by the big box stores," said Grafton-Cardwell. "This aspect is often overlooked by personnel only monitoring citrus and not closely related ornamentals. Also, fruit and plants that are trucked or flown into California from Mexico, Texas, Louisiana, Florida, and Hawaii could carry the insect."

The HLB disease was found in 2005 in Florida and is spreading throughout the state. HLB is transmitted by Asian citrus psyllid, grafting infected plant material, and possibly by citrus seed. The disease could arrive in infected citrus trees, infected budwood or infected psyllids. The best prevention for the disease is to use only certified budwood in commercial and homeowner plantings, and for people to follow quarantine rules and not import citrus illegally.

The California Department of Food and Agriculture and the Citrus Research Board have an HLB Task Force that has developed an action plan to respond to this pest and disease situation. If Asian citrus psyllid or HLB were to be found in California, an eradication program would go into effect.

For more information, visit the website If you think you have found the psyllid or disease, call your local County Agricultural Commissionerís office or the CDFA exotic pest hotline: 1-800-491-1899.

Stephanie Klunk