A Southern California quarantine zone has been expanded in an effort to stop the spread of a disease that threatens the state’s multibillion-dollar citrus industry.

The addition of 107 square miles (277 square kilometers) encompassing the cities of Corona and Norco and part of Chino followed the discovery of a dozen trees with citrus greening disease in Corona, The Press-Enterprise reported Thursday.

The quarantine zone now covers 1,127 square miles (2,919 square kilometers) in parts of Riverside, San Bernardino, Los Angeles and Orange counties.


The quarantine forbids movement of fruit, citrus plants or foliage, but the fruit can be consumed on properties where it was grown.

“Sometimes it’s hard, especially around the holidays,” said Riverside County Agricultural Commissioner Ruben Arroyo told the newspaper. “You have an orange tree or lemon tree with fruit, and you want to take it to your family.”

Citrus greening disease is also known as Huanglongbing or HLB. It is spread by a tiny aphid-like bug called the Asian citrus psyllid.


Infected trees develop mottled leaves, produce deformed fruit and eventually die.

Discovery of the first infected tree in the state occurred in 2012 at a home in the Los Angeles suburb of Hacienda Heights. The disease has since spread to 1,741 trees in Southern California.