biological control of canola rhizoctonia damping off by application of burkholderia cepacia

biological control of soil borne plant pathogens with antagonistic microorganism has been more attracting interest. especially, burkholderia strains have been intensively investigated as biological agents. the objective of this study was finding an effective biologica control agent against the canola damping off caused by rhizoctonia solani. rhizoctonia damping-off is one of the most important diseases of this industrial oilseed. all strains were selected on plates by dual culture using plant pathogenic fungus. two strains had antagotistic activity in pot test. according to morphological, biochemical and physiological tests, the isolate bu1 wase indentified as burkholderia cepacia. among these burkholderia strain, bu1 showed the most antagonistic effect on canola damping off. seed and soil treatment with the bacteria caused an average reduction in damping off and disease development, 56% and 62% respectively. results of the biocontrol mechanism tests showed that isolate bu1 produced antibiotic and volatile metabolite. the isolate was capable of producing sidrophore, protease enzyme and hydrogen cyanide. the strain was a strong colonizer of canola root and so increased plant growth.