Biological Control,Volatile,Non Volatile Antibiotics,Hyperparasitism,Saprophytic,Sterile soil,Antibiotic Substances,Phylloplane Fungi

Biological Control

	Biological Control Biological control is the reduction of inoculum density or disease producing activities of a pathogen or parasite in its active or dormant state by one or more organisms. This is accomplished naturally or through manipulation of the environment/host/antagonist or by mass introduction of one or more antagonists. Principles of Biocontrol Biocontrol is based on antagonism. Which is further based on competition (for nutrients and space), parasitism (by production of volatile non-volatile antibiotics) and hyperparasitism.
Competition In the soil, the dormant propagules of fungi are subjected to intense microbial competition when nutrients become available, e.g. Ammonium sulphate solution improves the biocontrol of Heterobasidium annosum by Trichoderma viridae. Hyperparasitism It is the attack of a secondary parasite on primary parasite (parasitism of one microbe by another) observed among airborne pathogens. Rusts are often parasitised by Enderluca carices and powdery mildews by Ampelomyces quisqualis. Cladosporium species parasitise both rust and powdery mildews.
Antibiosis It depends on competitive saprophytic ability of a fungus. Sterile soil does not produce antibiotic substances. Several phylloplane fungi such as Aureobasidium, Alternaria, Botrytis and Helminthosporium have been shown to produce antibiotics.