Due to the detection of the citrus disease huanglongbing, or citrus greening, the California Department of Food and Agriculture has put in place quarantine zones in certain area of southern California.  Some of these zones include large areas of the City of Walnut (generally east of Pierre Road.). To see the areas affect, you can visit the California Department of Food and Agriculture Quarantine Maps.

The quarantine areas prohibit the movement of all nursery stock out of the area, while maintaining existing provisions allowing the movement of only commercially cleaned and packed citrus fruit. Any fruit that is not commercially cleaned and packed, including residential citrus, must not be removed from the property on which it is grown, although it may be processed and/or consumed on the premises. 

For more information and to find out what to look for, visit www.CaliforniaCitrusThreat.org.

The disease is bacterial and attacks the vascular system of plants. IT DOES NOT POSE A THREAT TO HUMANS OR ANIMALS. The Asian citrus psyllid can spread the bacteria as the pest feeds on citrus trees and other plants. Once a tree is infected, there is no cure; it typically declines and dies within a few years. 

As the California Department of Food and Agriculture (CDFA) continues to fight to protect the state’s $3.4 billion citrus industry, it’s calling upon the help of a small, but mighty predator called Tamarixia radiata – a parasitic wasp. These beneficial wasps are being released in several California neighborhoods to reduce the population of the Asian citrus psyllid (ACP), the pest that spreads the deadly citrus tree disease, Huanglongbing (HLB).

This natural biological control is one of the many tools CDFA uses against HLB as the disease continues to be detected throughout the four Southern California counties of Los Angeles, Orange, Riverside and San Bernardino. Although HLB has not been found in a commercial citrus grove, more than 2,000 residential citrus trees in California have been infected with HLB and destroyed.

WHAT TO DO: 

The best way to protect citrus trees from the disease is to control the psyllid population.

• Inspect citrus trees for signs of the pest and disease each month or whenever watering, spraying, pruning or tending trees.
• Call the California Department of Food & Agriculture hotline at 1-800-491-1899 if any suspicious pests or symptoms of HLB are found. 
• Don’t bring any plant material into California from other states or countries and don't move citrus plants out of quarantined areas, because they might be carrying psyllids or be infected with HLB.
• Only buy citrus trees from reputable, licensed California nurseries. 
• Dry or double bag plant clippings before placing in green waste recycle bins to avoid moving psyllids and HLB-infected plant material.
• Cooperate with agriculture officials on detection and suppression efforts of the Asian citrus psyllid and HLB.

The Asian citrus psyllid was first detected in California in 2008 and is known to exist in Ventura, San Diego, Imperial, Orange, Los Angeles, Santa Barbara, San Bernardino and Riverside counties. If Californians believe they have seen evidence of huanglongbing in local citrus trees, they are asked to please call CDFA’s toll-free pest hotline at 1-800-491-1899. For more information on the Asian citrus psyllid and huanglongbing, please click here.