An Asian citrus psyllid feeds on a citrus tree in Florida.
An Asian citrus psyllid feeds on a citrus tree in Florida.

The California Department of Food and Agriculture has quarantined a 99-square-mile area of Santa Clara County around San Jose after multiple Asian citrus psyllids were found in a residential area.

The quarantine prohibits movement of citrus and curry tree nursery stock out of the quarantine area, according to a news release.

It also requires that all commercial citrus fruit be cleaned of leaves and stems before moving out of the quarantine. Commercial growers also can choose an alternative of treating the grove with an approved insecticide shortly before harvest.

The state is asking home owners not to move dooryard fruit out of the quarantine area.

In addition to part of Santa Clara County, citrus psyllid quarantines have been established in Imperial, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, Tulare, Ventura and portions of Fresno, Kern and San Luis Obispo counties.

The concern is the Asian citrus psyllid can spread the bacterial disease, citrus greening, also known as huanglongbing or HLB.

Although harmless to humans and animals, citrus greening weakens and even kills citrus trees.

Only one tree with greening has been confirmed in California, and that was in the Hacienda Heights region of Los Angeles County. The homeowner destroyed the tree shortly after confirmation.

In Florida, where the insect pest and disease have become endemic, they've caused more than $4.6 billion in losses to that state's citrus industry.