Innundative application- The biocontrol agent is applied directly to the infection court at high population level.ultimum and bacteria suppress the damping off disease in cucumbers.įluorescent iron chelator siderophores such as Pseudobactins and pyoverdins produced by P.fluorscence chelate the iron available in the soil, thereby, depriving the pathogen of its Fe requirement Ex.- The competition for nutrients between pythium aphanidermatum, P. The biocontrol agent competes for food and essential elements with the pathogen thereby displacing and suppressing the growth of pathogen. Produces antibiotics Viz- Trichodermin, Gliotoxin and viridian. The antibiotic compounds secreted by the biocontrol agent suppress the growth of the pathogen.Įx – Phenazine-1-carboxylic acid (PCA) produced by Pseudomonas fluorescence play an important role in suppressing the take all disease of wheat, Trichoderma sp. Produces chitineses and B 1-3 glucanases which lysis the cell wall of Rhizoctonia solani. The chitinolytic enzymes of Serratia marcescens caused cell wall lysis of Sclerotium rolfsi. Causes hyphal lysis of gaumanomyces gramini. Various bactria and fungi secrete hydrolytic enzymes for the degration of cell wall of pathogen.īacillus sp. Pathogen by puncturing the host hyphae and kills them. The biocontrol agent parasitizes the pathogen by coiling around the hyphae.Įx – Tricoderma viride parasite derives its nutrition from the Mechanism involved in biological control :. ,įusarium spp., Macrophomina phaseolina, Pyricularia oryzae, Pythium spp., Rhizoctonia solaniĪlternaria brassicola, Fusarium oxysporum f. Solani, Pythium sp.įusarium spp., Pythium spp., Rhizoctonia spp., Sclerotium rolfsii, Streptomyces scabies, Verticillium spp. Macrophomina phaseolina, Pythium, Sclerotium rolfssiįusarium oxysporum f.sp. The reduction of inoculums density or disease producing activities of a pathogen or parasite in its active or dormant stage by one or more organisms accomplished naturally or through manipulation of the environment, host or by introduction of one or more antagonists. However, their use poses certain problems of residues left over on crops, which has gained considerable importance in recent years, not only in India but also throughout the world. Although several methods are followed for this purpose, disease control by chemicals is the promising one especially under intensive cropping programmes. Therefore, control of plant diseases assumes greater importance. The losses are going to increase with change in agricultural practices and our country, which is tropical with warm and humid climate, provides ideal conditions for development and spread of diseases of crops cultivated under good management systems.
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Biocontrol Agents and Mechanism Involved in Biological ControlĪccording to the estimate of FAO, the annual losses to crop production due to plant diseases alone are about 12 per cent.