There’s no threat to human health in a growing quarantine in Southern California, but an annual $2 billion worth of citrus fruits are at risk in a war with a tiny insect and the bacteria its spreads.

Earlier this month, the state of California added 93-square miles in the Hacienda Heights area of Los Angeles County to the quarantine after the citrus greening disease known as huanglongbing was discovered in the state for the first time.

Until then, California had been combatting the insect that precedes the disease, which does not harm humans or animals, but causes citrus trees to decline and eventually die.

Now covering most of Southern California, the quarantine means no nursery stock can be moved out of the area and only commercially cleaned and cleared citrus fruit may be shipped from there. Residential citrus can’t be removed from the property on which it’s grown, although it can be processed and consumed on the premises.

“The success of any quarantine depends on cooperation from those affected,” says Karen Ross, secretary of the California Department of Food and Agriculture (CDFA), in a news release.  “The stakes could not be higher for California citrus.”

The tiny insect known as Asian citrus psyllid spreads the huanglongbing bacterium and the disease it causes is fatal to citrus trees. As yet, there is no remedy. Before an infected tree dies, it will produce only bitter, misshaped fruit.

That’s why California’s entire $2 billion citrus industry, along with its cultivation of 300,000 acres of citrus trees, are at risk. The insect was discovered in the state in 2008, and both the industry and agricultural officials have been fighting an aggressive battle ever since.

Ted Batkin, president of the California Citrus Research Board, has called the insect-borne tree killer “a kick in the stomach.” Huanglongbing has already ravaged citrus growing areas in China, Brazil and Florida. Since showing up in California, the insects have also been found in Texas, Arizona and several other states.

CDFA officials say because the latency period for development of huanglongbing symptoms in an infected tree can be two years, the current quarantine is expected to last at least that long. The strategy remains to control the spread of the insect while California’s researchers work to come up with a cure. 

The quarantine now includes all or part of Ventura, San Diego, Imperial, Orange, Los Angeles, San Barbara, San Bernardino and Riverside counties. Backyard citrus trees have a lot to do with not only how Southern California looks, but also how it smells.   

The infected tree taken from the Hacienda Heights yard of a suburban homeowner was first sprayed to eliminate the psyllids. The tree was then dug up, placed in a sealed bag and taken away in a van to a state lab.

 

Asian citrus psyllid (ACP) photograph courtesy USDA