Journal of Citrus Pathology

Asian citrus psyllid (ACP) was first detected in southern California in September 2008 in the urban landscape.  Since that time, the California Department of Food and Agriculture has conducted an eradication program utilizing systemic imidacloprid and foliar cyfluthrin wherever psyllids are detected.  This program was halted in Los Angeles County in 2011 because of the size of the ACP infestation. Psyllids have continued to spread to the east and the south into San Bernardino, Riverside, and Orange Counties. In areas such as San Diego and Imperial counties where urban treatments have been continuous, detections of ACP in commercial citrus are rare and a single treatment of a combination of two broad spectrum insecticides reduces psyllids below detectible levels for many months.  In contrast, in San Bernardino and Riverside counties where re-infestation from urban areas is a continuing problem and where the treatments are not well-coordinated in an area-wide fashion, psyllids have become established and commercial growers must treat multiple times per year.  The University of California in collaboration with the California Citrus Pest and Disease Prevention Committee have developed strategies for managing ACP once it establishes in commercial citrus. In the initial phase of invasion, when ACP densities are low, aggressive applications of two broad spectrum insecticides are recommended.   In areas where the psyllid has become established, area-wide treatment programs utilizing 3-5 insecticides/year are necessary directed at periods of flush and also at the late fall and early spring overwintering populations.  Insecticide choices are based on considerations of efficacy, control of other pests, costs, preservation of natural enemies and resistance management.