Efficacy of Bacillus spp. in the management of collar rot of Gerbera under protected cultivation

The incidence of collar rot of Gerbera jamesonii Bolus ex Hook (Sclerotium rolfsii) was recorded in a survey during 2013–14 in Ooty and Yercaud, Tamil Nadu, India. The mean value of rot incidence was 6.95% in various varieties. In vitro screening was done with 26 isolates of Bacillus spp. against collar rot pathogen. Among them, five strains of Bacillus spp. showed highest antagonistic activity against S. rolfsii. Also the crude antibiotics were extracted from these strains and tested against the pathogen in vitro. An extensive study of antimicrobial compounds was done by subjecting the strain BSD 1 to GC/MS analysis. The effective strains were applied through root dipping and soil drenching @ 5 ml/l either individually or in consortia in polyhouse and their efficacy was tested in relation to disease incidence and growth parameters of Gerbera.