Potentially devastating citrus tree disease found in Oceanside

People pick oranges
La Mesa Rotary Club members pick oranges recently in the backyard of a home in the San Carlos area of San Diego for delivery to in-need people.
(Karen Pearlman)

State agricultural officials declared a 60-square-mile quarantine this week after a potentially devastating citrus disease was found in two trees on residential property in Oceanside, its first appearance in San Diego County.

The bacterial disease called Huanglongbing, also known as HLB or “citrus greening,” is spread by the Asian citrus psyllid, a small insect that feeds on citrus tree leaves. The disease has been confirmed in Orange, Los Angeles, San Bernardino and Riverside counties.

Infected trees cannot be cured. They will produce bitter and misshapen fruit and eventually die, with the chance that the insect will spread the disease to nearby trees. Signs include blotchy yellowing of leaves; yellow shoots; small, lopsided fruit; and premature, excessive fruit drop.


“Our goal is to stop this from spreading any further,” San Diego Agricultural Commissioner Ha Dang said in a news release. “By working together, we can all protect San Diego County’s $150-million citrus industry.”

The quarantine area is bordered on the north by Vandegrift Boulevard, on the south by Carlsbad Village Drive, on the east by Melrose Drive and on the west by the Pacific Ocean.

People and businesses within the quarantine are prohibited from moving citrus nursery stock, plant parts and fruit outside the boundaries except for commercially cleaned and packed fruit that adheres to specific requirements. Residential citrus plants and parts may not be moved from the properties where they are grown.

As of April 2020, Orange County had the highest number of HLB detections: 1,370 positive trees out of more than 1,860 found statewide.

Commercial growers in the quarantine area can contact Sandra Zwaal with the California Citrus Pest & Disease Prevention Program at for more information.

Diehl writes for the San Diego Union-Tribune.