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Incurable citrus disease triggers quarantines
Turlock & rest of California impacted
UC Agriculture and Natural Resources encourage citrus tree owners to monitor for Huanglongbing which is fatal for citrus trees. If trees become infected with the disease there is no cure and the tree will die. - photo by CANDY PADILLA/The Journal

Two more trees that have been infected by Huanglongbing disease have prompted quarantines throughout Southern California, adding on to the existing quarantines that are now in place in 17 California counties.

As a result, the University of California Agriculture and Natural Resources Cooperative Extension is urging citrus owners throughout the state to remain vigilant in the face of the incurable disease.

“We believe 60 percent of Californians have at least one citrus tree in their yard, so HLB could have a devastating effect on the California residential landscape,” said Beth Grafton-Cardwell, UC ANR Cooperative Extension citrus entomology specialist.

The recent discovery of an HLB-infected lime tree and kumquat tree in residential areas of San Gabriel Valley this month has resulted in an 87-square mile quarantine, adding on to the existing quarantine in the Hacienda Heights area after a multi-grafted citrus tree was found to be infected in March 2012.

“So far, the bacterium that causes HLB has been found infecting only three trees, which have all been destroyed,” said Grafton-Cardwell. “However, it is highly likely there are other infected trees in California.”

“It will be critical for all Californians to assist with efforts to reduce psyllids and detect and remove infected trees to prevent this disease from devastating California citrus,” continued Grafton-Cardwell.

HLB is spread by the Asian citrus psyllid, an invasive insect that feeds on the leaves and stems of citrus trees. After an Asian citrus psyllid feeds on an infected tree, it carries the disease-causing bacteria for life and can transfer the disease when feeding on other citrus trees. 

An early indication of HLB is the yellowing of leaves on an individual limb or one sector of the tree’s canopy, according to a UC ANR Integrated Pest management Program Pest Note. These leaves will show an asymmetrical pattern of blotchy yellowing or mottling.

Although HLB does not pose a threat to humans or animals, a citrus tree infected with the disease typically declines and dies within a few years. Trees found to be infected with HLB are destroyed and removed in order to prevent the disease from spreading to surrounding citrus trees.

Quarantines put in place for the Asian citrus psyllid prohibit the movement of untreated or unprocessed citrus fruits and trees from the area, although they may be processed or consumed within the quarantine boundaries.

Additionally, citrus owners in areas where Asian citrus psyllids are found can treat their trees with insecticides in order to prevent HLB infections.

“The success of any quarantine depends on cooperation from those affected,” said CDFA Secretary Karen Ross. “The stakes couldn’t be higher for California citrus.”

Those who believe they have found an Asian citrus psyllid or encounter a citrus tree that is exhibiting symptoms of HLB are urged to call the CDFA hotline at 1-800-491-1899 immediately.