Introduction
Increasing demand from society for healthy foods with less chemical residues, concerns about air and
water pollution caused by chemicals and the negative ecological impact of agrochemicals has
prompted research on more environmentally friendly alternatives to those traditional methods
(Alabouvette et al., 2006). In recent years, biological control has been identified as a promising method
to control plant diseases and pests using microbial antagonists, and the number of manufactured
biocontrol products is steadily increasing.
1.4.2 Definition of biological control
There are many definitions of biological control of plant diseases. According to Baker and Cook (1974)
biological control is “the reduction of inoculum density or disease-producing activities of a pathogen or
a parasite in its active or dormant state, by one or more organisms, accomplished naturally or through
manipulation of the environment, host or an antagonist, or by mass introduction of one or more
antagonists”. Later, they defined it as “the reduction in the amount of inoculum or disease-producing
activity of a pathogen accomplished by or through one or more organisms other than man” (Cook &
Baker, 1983). However, Mukherjee et al. (2008) more recently defined biological control as “the
purposeful utilization of introduced or resident living organisms, other than disease resistant host
plants, to suppress the activities and populations of one or more plant pathogens”.
Thus, biological control is an environmentally friendly method to suppress plant diseases and is
considered the best alternative to or supplemental method for reducing chemical application in
agriculture (Emmert & Handelsman, 1999).