Influence of imidacloprid soil treatment rates, soil texture, and irrigation regimes on imidacloprid titers in leaf terminal tissue

To control the spread of Asian citrus psyllid, Diaphorina citri, (ACP) from citrus nursery trees sold at retail locations within the ACP quarantine areas of Southern California, the California Department of Food and Agriculture issued treatment guidelines that were intended to protect the trees through at least three months. During 2011, several citrus trees at retail nursery stores within Los Angeles which were allegedly treated with imidacloprid within three months were found to have active psyllids. This study was undertaken to determine the impact of the rate of imidacloprid, irrigation regime, and container soil texture on the magnitude of imidacloprid titers in citrus leaf tissue and longevity of protection from ACP.