For the last few years citrus growers in the San Joaquin Valley have been nervously watching the establishment of Asian citrus psyllid in southern California and bracing themselves for the day of northward movement. That day arrived in November 2012 when two psyllids (Strathmore 16 Nov. and Terra Bella 21 Nov.) were caught on yellow sticky card traps, in addition to a third capture back in January 2012. These captures have now resulted in restrictions on the movement of citrus in the heart of California's principal citrus production region.

Asian citrus psyllid is a small insect the size of an aphid that feeds on citrus leaves and stems. It is the vector of a deadly bacterial disease of citrus called huanglongbing, often referred to as HLB or citrus greening. This pest and disease combo has resulted in devastating losses to the citrus industry in Florida, and has the potential to have a similar effect in California.

Prior to November 2012 Asian citrus psyllid had been reported in eight California Counties, mostly in the southern part of the state, with a combined total of approximately 26,000 square miles under quarantine.

However, the two finds in Tulare County mark the first time the psyllid has been found in the heart of California's principal citrus production region of the lower San Joaquin Valley: citrus production in Kern, Tulare and Fresno counties totals more than 200,000 acres at an annual value of approximately $1.7 billion.

The capture of individual psyllids on sticky traps in Strathmore and Terra Bella gives CDFA the authority to establish a quarantine of citrus within a 20-mile radius of the find in Strathmore. As an interim step, CDFA has opted to only regulate citrus in a 5-mile radius around each find. Further trapping and delineation can determine if psyllids are truly established in the region, or if the psyllids caught were just non-breeding hitchhikers brought to the corridor along State Highway 65 from infested counties in Southern California. Within the five-mile regulated area is an eight-hundred meter eradication zone requiring mandatory treatment of all host plants. If further delineation detects an established population it is anticipated that quarantines would be established. If established, a quarantine for Asian citrus psyllid would last a period of two years from the most recent capture. If additional psyllids were captured during the two-year quarantine the clock would reset itself for another two years.

Harvesting, shipping options

Due to the fact that the psyllid only feeds on leaves and stems (and not fruit), citrus growers within quarantine zones in California have several options for harvesting and shipping fruit. Fruit harvested within quarantine zones can be picked, transported and packed within the quarantine zone without restrictions. Once clean fruit is packed (no leaves or stems) it can be shipped to locations outside of the quarantine.

Packing fruit from within the quarantine at packing houses outside of the quarantine is also possible under a CDFA compliance agreement that can be accessed through the County Agricultural Commissioner.

These agreements state that the grower is willing to comply with CDFA and USDA regulations regarding the movement of bulk citrus, the most important of which is that bulk citrus must be processed through trash-removal equipment (to remove all leaves and stems) before it is shipped in bulk to a packer outside of the quarantine.

The Asian citrus psyllid quarantine also affects retail nursery stock. Currently there are compliance agreements and protocols available that allow retail nursery stock to be moved within the quarantine zone.

However, no provisions are currently available to move nursery stock from the quarantine zone to regions outside of the quarantine zone unless the plants were budded and produced within a federally-approved screenhouse facility.

Regulations regarding Asian citrus psyllid can change quickly. For that reason citrus growers are encouraged to maintain good contact with their local Agricultural Commissioner. Additional information on the status of quarantines and other restrictions can be found online at http://www.cdfa.ca.gov/plant/acp/.