Detection, characterization and management of brinjal little leaf disease in Assam

Aim: To record the prevalence, detection, molecular and biological characterization of phytoplasma associated with brinjal little leaf disease in Assam and its management. Methodology: Roving survey was conducted during the 2018-2020 brinjal growing seasons to record the disease incidence and symptoms associated with the disease. Insect and dodder transmission studies were carried out along with tetracycline tests. Further, molecular detection of all the samples collected during the survey and after dodder and insect transmission studies were done through PCR assays by using universal primers. Results: The disease incidence varied from 3.62 to 23.63 per cent in surveyed districts. Transmission studies revealed that Hishimonus phycitis (Dist.) is acting as a vector of brinjal little leaf phytoplasma and found to be transmitted by dodder (Cuscuta campestris). The phylogenetic analysis indicated that the Brinjal little leaf phytoplasma understudy was associated with ‘Candidatus phytoplasma trifolii’ and plants like Datura stramonium play a major role as potential alternate host of the phytoplasma. Further, studies on the effect of the antibiotic tetracycline hydrochloride in managing the disease elucidated that the antibiotic was effective only for temporary remission of symptoms. Interpretation: This study reveals a broad picture about the incidence, phytoplasma associated with the disease, putative leafhopper vector transmitting the phytoplasma in the field, alternate host harbouring the phytoplasma, and effect of antibiotic on the disease suppression, which will be useful to develop effective management strategies.