ABSTRACT
Biological control or biocontrol is employment of one or more organisms to eliminate or reduce the disease or damage caused by another. The biological methods of plant disease management include the use of antagonistic microorganisms or biocontrol agents, cross protection, hypovirulence, bacteriophages, use of plant products, etc. Biocontrol agents (fungi and bacteria) are used in the control of plant diseases and are highly effective in the nursery diseases and in fields where commercial crops are grown. The biocontrol agents control the plant diseases by the following general mechanisms: parasitism, antibiosis, competition, lysis and induced systemic resistance. Plants are surrounded by diverse types of mesofauna and microbial organisms, some of which can contribute to biological control of plant diseases. Microbes that contribute most to disease control are most likely those that could be classified competitive saprophytes, facultative plant symbionts and facultative hyperparasites. The phenomenon of cross protection has been established in some of the bacterial diseases in plants.
