Chemical Control of the Asian Citrus Psyllid and of Huanglongbing Disease in Citrus

By 2014, huanglongbing (HLB), the most destructive disease of citrus, and its insect vector, the Asian citrus psyllid (ACP), Diaphorina citri (Kuwayama), became established in all major citrus-growing regions of the world, including the United States, with the exception of California. At present, application of insecticides is the most widely followed option for reducing ACP populations, while application of antibiotics for suppressing HLB disease/symptoms is being practiced in some citrus-growing regions. Application of insecticides during the dormant winter season, along with cultivation of HLB-free seedlings and early detection and removal of symptomatic and asymptomatic trees, has been very effective in managing ACP. Area-wide management of ACP by application of insecticides at low volume in large areas of citrus cultivation has been shown to be effective in managing HLB and reducing management costs. As insecticide resistance is a major problem in sustainable management of ACP, rotation/alternation of insecticides with different chemistries and modes of action needs to be followed. Besides control of the insect vector, use of antibiotics has temporarily suppressed the symptoms of HLB in diseased trees. Recent efforts to discover and screen existing as well as new compounds for their antibiotic and antimicrobial activities have identified some promising molecules for HLB control. There is an urgent need to find a sustainable solution to the HLB menace through chemical control of ACP populations and within HLB-infected trees through the judicious use of labeled insecticides (existing and novel chemistries) and antibiotics in area-wide management programs with due consideration to the insecticide resistance problem.