Surveys were conducted in some citrus-growing parts of Manipur, Northeast India for recording the incidence of "Huanglongbing" (HLB) symptoms. The purpose of this study was to confirm the presence of HLB in citrus orchards in different geographical locations of Manipur and to correlate the disease incidence with variation in elevation of the region. The presence of "Candidatus Liberibacter asiaticus" was detected in ten regions in Manipur using PCR with species-specific primers for "Ca. Liberibacter asiaticus." A total of 128 (19.6%) of 653 samples were positive for "Ca. Liberibacter asiaticus." The incidence was found to be highest (30.0 to 45.7%) in the lower elevation (700-1200 m above sea level) and was found to be least (5.0 to 10.0%) in higher elevation (1200-1500 m above sea level). HLB was detected in citrus species, viz., Citrus maxima, Citrus jambhiri, Citrus macroptera, Citrus medica, and Citrus reticulata. Sequencing of the 16S rRNA amplicon fragment and their phylogenetic analysis showed that these sequences clustered together with other "Ca. Liberibacter asiaticus" sequences from the rest of the world. Our results revealed the widespread occurrence of HLB in all economically important citrus species of Manipur as well as significant variation in the incidence of HLB across different elevations. The present scenario in Manipur calls for effective disease management strategies. Extension programs should be conducted to create awareness of HLB among the citrus growers to reduce the spread of HLB and preserve the citrus cultivation in this Indo-Burma biodiversity hotspot region.

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