Citrus Huanglongbing (HLB): Diagnostic and management options

“Huanglongbing” (HLB) or citrus greening is the most devastating diseases of citrus that affects all cultivars causing systematic death of trees worldwide. The disease is associated with the presence of the phloem-limited α-proteobacteria ‘Candidatus Liberibacter asiaticus’, ‘africanus’, and ‘americanus’. The Asian Citrus Psyllid (ACP), is the main vector that transmits the pathogen while feeding the leaves of citrus trees, affecting fruit traits including fruit shape and size, ripening, and quality of fruits and compromising plant health, eventually leading to economic loss to the citrus industry. In this review, the history of HLB, its pathosystem, and geographical distribution with a primary focus on the various diagnostic measures that are in practice are described. The HLB identification in the field is the most challenging task for the growers as the symptoms of asymmetrical, blotchy mottling patterns on leaves are often confused with nutritional deficiency. The unavailability of precise methods for identification of HLB at the initial infection is of major concern. Hence, the development of field-based detection methods could help citrus growers to take protective measures to minimize disease spread in citrus plantations. The review also highlights the existing detection and management options of HLB as well as the perspectives in this research field.