survey of bacillus spp. isolates for biological control of white rotof garlic caused by sclerotium cepivorum under in vitro and greenhouse conditions

sclerotium cepivorum incited white rot is one of the destructive diseases of garlic inhamedan province. a total number of 175 bacillus strains were isolated from soil and fromgarlic rhizospheres. the antagonism of the bacterial isolates against sclerotium cepivorum wasevaluated using dual culture method. ten high level activity isolates which produced inhibitionzones were selected for further study. physiological, biochemical, and morphologicalcharacteristics of the isolates revealed that they belonged to the species of bacillus. antifungalactivity of the liquid and volatile metabolites produced by the bacterial isolates on pathogenand as well, their ability to produce the enzyme protease and hydrogen cyanide were studied.all the isolates produced volatile as well as liquid metabolites, reducing disease significancethrough their different effects. isolates b9, b21 and b12 produced protease, but none producedhydrogen cyanide. the antagonistic activity of bacterial isolates was evaluated against thepathogen, employing soil and seed treatment methods. greenhouse trial results indicated thatall the isolates were able to control the severity of the disease, but isolates b12, b21, b3, b20,and b9 showed their effects in either one of the experimental methods more than 73% isolatesb3 and b21 showed the most effects on reduction of the disease (73-83.3%). all the isolatessignificantly (p≤0.01) promoted growth factors in garlic plant.