The California Department of Food and Agriculture has expanded the Asian citrus psyllid quarantine in Tulare County to 856 square miles after additional psyllids were trapped there.
The new quarantine is 110 square miles, adjacent to existing quarantine, is bordered by Avenue 384, Road 180, East Main Street and road 80, according to a news release.
The quarantine is expected to increase since a single psyllid was detected west of Exeter near Farmersville.
The exact size has yet to be determined.
The state's citrus growers are concerned because Asian citrus psyllids can spread citrus greening, a bacterial disease also known as huanglongbing.
Although harmless to humans, the disease can weaken and even kill citrus trees. In Florida, where greening is endemic, it has caused at least $3.6 billion in economic losses.
The disase also has been confirmed in Georgia, Louisiana, South Carolina and Texas.Only one greening-infected tree has been confirmed in California, and that was in Hacienda Heights in the Los Angeles basin. The tree's owner removed and destroyed the tree.