Save our citrus from citrus greening

Huanglongbing Detected on LA County Pre-Symptomatic Kumquat Tree


By Patrick Cavanaugh, Farm Director; Laurie Greene, Editor, California Ag Today



#CitrusMatters (provided by Bayer CropScience, in partnership with California Citrus Mutual)

“It’s disappointing, but fortunately it was found in a residential area,” commented Joel Nelsen, president of California Citrus Mutual (CCM), on the second discovery of Huanglongbing  [wong-long-bing] (HLB), or citrus greening, in California. CCM refers to HLB as “a death sentence for California citrus” as once the plant is infected with this bacterial disease, there is no known cure.

Joel Nelsen

Joel Nelsen, president, California Citrus Mutual

“HLB was detected in plant material taken from a kumquat tree in a residential neighborhood in the San Gabriel area of Los Angeles County,” Nelson stated. “The 20-year-old tree was in the front yard of a residence and had not yet shown any symptoms.”

The San Gabriel neighborhood is located about 15 miles from Hacienda Heights, where the first HLB case in the state was detected in 2012 in a residential citrus tree. The  An aggressive trapping program for the Asian citrus psyllid (ACP), a pest known to spread the HLB bacteria as it feeds on citrus trees and other plants, has been ongoing ever since this first finding, including in the San Gabriel area.

“It’s fortunate that the homeowner is quite cooperative,” said Nelsen, “and other neighborhood homeowners are allowing officials to run PCR tests (polymerase chain reaction) on samples of their trees to determine if the disease is present.” PCR analysis is a sensitive research technique for detecting and identifying small numbers of bacteria in plants via DNA amplification.

Nelsen declared, “This find is exactly what the Citrus Pest and Disease Prevention Program is designed to do. PCR testing of a random sampling of leaves and stems in the area, as our program prescribes, enabled us to hit a positive” before symptoms appeared.

“We do not know how long the tree had been diseased,” said Nelsen, “but we do know that we have been trapping ACPs there for a long time and had not found any HLB before. You do not want to

Citrus Pest & Disease Prevention Program

find anything,” Nelsen said, “but when you do, you want to find it before it becomes an epidemic.”

In a statement on Friday, California Department of Food and Agriculture (CDFA) Secretary Karen Ross said, “Citrus is a cherished part of our landscape and our shared history, as well as a major agricultural crop.” CDFA has been planning and preparing for HLB detections since before the first ACP was detected in the state in 2008. Quarantines are now in place in 17 California counties.

Los Angeles County Agricultural Commissioner Kurt Floren will mobilize his team over this week to check on citrus trees in plant nurseries that fall within the 800-meter radius around the infected tree area. A spray protocol is already in place for all citrus trees within the 800-meter radius.

“More traps are going out so we can try to delineate the scope of the problem. Hopefully it will be nothing more than this one tree, like the solitary diseased tree we found in Hacienda Heights,” Nelsen said.


To support the citrus industry in its fight against HLB, go to California Citrus Mutual Action Center.


For questions about the ACP or HLB, visit or call CDFA’s toll-free pest hotline at 1-800-491-1899.


View the Distribution Map  of ACP, HLB and parasites in California published by the UNIVERSITY OF CALIFORNIA Division of Agriculture and Natural Resources.

USDA's free "Save Our Citrus" iTunes app

USDA’s free “Save Our Citrus” iTunes app


Visit the Citrus Pest & Disease Prevention Program.


Verify plant symptoms at USDA’s SaveOurCitrus website.


For information and ACP solutions, go to #citrusmatters, provided by Bayer CropScience, in partnership with California Citrus Mutual