San Francisco County in the U.S. state of California has been placed under a plant pest quarantine for the Asian citrus psyllid (ACP) following the detection of one insect in San Francisco’s Marina District. 

The California Department of Food and Agriculture (CDFA) said the ACP is an invasive species of grave concern because it can carry the bacteria that causes the disease Huanglongbing (HLB), also known as citrus greening disease.

All citrus – including oranges, mandarins, lemons, kumquats, pomelos, and limes, and related plants, such as curry leaf trees - are susceptible hosts for both the insect and disease. 

There is no cure once a tree becomes infected with HLB. The diseased tree will decline in health, produce bitter, misshapen fruit, and eventually die.

In California, HLB has been detected at residential properties in Los Angeles, Orange, and Riverside Counties. ACP quarantines are already in place in 27 counties in the state.