This review article emphasis that biological control is one of the substitutes to chemical method for the usage of antagonistic micro-organism to suppress disease causing plant pathogens. Plant and pathogens come up different interactions in their life cycles which significantly determine the fate of plant health. Biological control agents have a series of different mechanisms to suppress plant pathogens which depends on the nature of antagonistic organisms like competition, antibiosis and mycoparastism. The better effect of biocontrol needs experiences and preferable managements. Biocontrol can be performed well under controlled condition, but sometimes, it fails in the field due to some complex environment factors. Application of biocontrol could be improved by understanding the effective environment parameters, biology of antagonistic organisms and pathogens as well. Trichoderma spp is a successful example of biocontrol which has been used in order to control different plant pathogens successfully.

Keywords: Biocontrol; Plant pathogen; Trichoderma spp.