ABSTRACT
Biological control of plant pathogens accomplished through host resistance and cultural practices has been working for decades and continues to be a predominant disease control strategy. There is much disagreement on what constitutes biological control. Antagonism was the major basis for this definition and all those practices by which antagonism, including antibiosis, competition and exploitation could be achieved were included under biological control methods. Antibiosis is defined as the condition in which one or more metabolites excreted by an organism have a harmful effect on one or more other organisms. Competition for nutrients or oxygen or both is probably responsible for a significant percentage of failure and endolysis of germlings of fungi. Exploitation in which species A inflicts harm by the direct use of species B for its own benefit. Exploitation is a condition wherein an organism directly harms another organism to get benefit out of the harm done to the organism.
