The most sustainable and environmentally acceptable control can be achieved using biocontrol agents through efforts to reduce the use of agrochemicals and their residues in the environment and in food (Haggag and Abdel-latif 2007). The identification, understanding and use of microorganisms or microbial products to control plant diseases and improve agricultural production are an integral part of sustainable agriculture. Biological control is an effective way to reduce damage caused by plant pathogens (Haggag 2002; Jeyarajan and Nakkeeran 2000). Biological control of plant diseases can be accomplished by different mechanisms, generally classified as antibiosis, competition, suppression, direct parasitism, induced resistance, hypovirulence and predation (Johnson and Curl 1972; Chaurasia et al. 2005). Antagonistic activity has often been associated with the production of secondary metabolites (Haggag and Abdel-latif 2007; Silva et al. 2001). Plant-associated microorganisms perform important functions for plant growth and health. These rhizospheric microorganisms could be exploited for their countless properties and active metabolites (Tamilarasi et al. 2008). Biological control of plant diseases is defined as “the use of beneficial microorganisms, such as specialized fungi, yeasts or bacteria, to attack and control plant pathogens (i.e. fungi, bacteria, nematodes or weeds) and the diseases they cause. (Fravel 2005). Biocontrol is a powerful way to reduce damage caused by plant pathogens (Jeyarajan and Nakkeeran 2000). The relationship between PGPR and biocontrol is not only important but also interesting. A biocontrol strain must be able to protect the host plant from pathogens and fulfill the requirements...... middle of paper...... for a considerable period of time. The carrier must display two fundamental properties; it must support the growth of the target organism and maintain the desired population of inoculant strains for an acceptable period of time. The media can be biological or non-biological. It should be economical, easily available and have a long shelf life. The media should be nearly sterile, chemically and physically uniform, have high water-holding capacity, high water retention, be suitable for as many bacterial species and strains as possible, and promote growth and survival. It must be easily manufactured, modifiable as a nutrient supplement, with a near neutral or easily adjustable pH, manageable in mixing, curing and packaging operations. Non-toxic, biodegradable, non-polluting, minimizes environmental risks such as dispersion of cells into the atmosphere or groundwater..