Charcoal stump rot, a primary root disease of tea caused by Ustulina zonata prevalent in Temi Tea Estate, Sikkim and its management through the application of beneficial soil microorganisms has been considered as a valuable tool to improve productivity without damaging the soil environment. In the present study, attempts have been made to isolate and study the potential rhizospheric microflora of tea plants and incorporate their use in this plantation crop. One each of the dominant AMF ( Glomus mosseae) and PGPR ( Bacillus pumilus) obtained from tea rhizosphere were selected for field application for the suppression of root rot pathogen ( U. zonata). Plant growth promoting activities as well as disease suppressive mechanisms viz solubilisation of phosphate, siderophore and IAA production were also evaluated in vitro condition followed by field trials with single or joint inoculation with the selected AMF and PGPR. Plant growth parameters such as increase in shoot length and number of leaves were noted. Inoculation of tea plants with G. mosseae and application of B. pumilus followed by inoculation with U. zonata revealed that both the treatments reduced the disease incidence in relation to untreated control. Enhanced accumulation of phenol as well as enzyme activities in PGPR and AMF treated plants were observed in relation to untreated control. Dual application revealed better results than single application. New isoform of catechin was observed in treated plants as evident in HPLC analyses. Survival of B. pumilus in soil was determined using serological assays.
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