Sclerotium cepivorum Berk. in onion (Allium cepa L.) crops: isolation and characterization of bacteria antagonistic to the fungus in Queensland

Bacteria antagonistic to the fungal pathogen Sclerotium cepivorum Berk., which causes onion white rot disease, were isolated and characterized. Eighty percent of the bacterial antagonists isolated from soil samples and sclerotia of S. cepivorum recovered from soil were identified as belonging to the genus Bacillus. The other antagonists were coryneforms and Pseudomonas spp. In contrast, 90% of the antagonists isolated from onion roots were mostly Pseudomonas spp. and the remainder were Erwinia spp. The significance of these antagonistic bacteria is discussed in relation to the control of white rot disease of onion.