BIOLOGICAL CONTROL OF PATHOGENS CAUSING THE CYMBIDIUM PSEUDOBULB ROT COMPLEX USING FLUORESCENT PSEUDOMONAS STRAIN BRL1
S. Sen, M. Rai, R. Acharya, S. Dasgupta, A. Saha, K. Acharya
Cymbidium, a commonly grown orchid of the Eastern Himalayas of India, suffers from huge crop losses due to an epidemic of pseudobulb rot since 1995. The disease is caused by the synergistic activity of three pathogens, Fusarium oxysporum, Mucor hiemalis f. sp. hiemalis and Pectobacterium carotovorum subsp. carotovorum. A rhizosphere bacterium, identified as a fluorescent Pseudomonas, named BRL-1, showed both in vitro and in vivo antagonistic activity against these pathogens. Our results show that antimicrobial activity of the isolate might be linked with the production of siderophores, proteases, chitinases and indole acetic acid (IAA). A talc-based formulation of the antagonist did not only protect Cymbidium plants from the disease but improved also its growth.