%Prompted by additional finds of Asian citrus psyllid, the California Department of Food and Agriculture has expanded the quarantine in San Luis Obispo county to 268 square miles.
The quarantine in and around the city of San Luis Obispo encompasses 97 square miles, according to a news release.
Around the unincorporated areas of Cayucos, the quarantine measures 61 square miles.
These are in addition to an existing quarantine in the Arroyo Grande area of the county.
The quarantine prohibits movement of home-grown fruit to outside areas, but the fruit can still be consumed within the quarantine areas.
Commercially grown fruit can move to the outside as long as growers meed specific criteria.
The quarantines are designed to prevent the movement of Asian citrus psyllid, the insect that spreads citrus greening.
Although citrus greening is harmless to humans and other animals, it can weaken and even kill citrus trees.
In Florida where the disease is endemic, it has cost that state's citrus industry more than $4.6 billion in losses, according to University of Florida figures.
Citrus greening has only been confirmed once in California, and that was in 2012 in a residential citrus tree in the Hacienda Heights area of Los Angeles County. the tree was destroyed by the homeowner.