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Biological control
- 1. BIOLOGICAL CONTROL OF PLANT DISEASES
- 2. Biocontrol agent Any practice which reduce the survival or activity of pathogen through other living organism which results reducing disease incidence (Garrett -1970) • Living organism – Antagonist
- 3. Two types Fungal biocontrol agent • Eg. Trichoderma viride • Trichoderma harzianum Bacterial biocontrol agent • Eg.Pseudomonas fluorescence • Bacillus subtilis
- 4. Advantage • Low cost • Safe to environment and person who apply them. • Gives protection throughout the life • Encourage soil microflora and increase yield • Easy to manufacture • Combined with bio- fertilizer.
- 5. Disadvantage • Only used against specific disease • Slow effect than the fungicides • Preventive not curative method • Required skilled persons
- 8. Mechanism of bio-control • Parasitism • Competition • Antibiosis • Lysis • Induced Systemic Resistance
- 9. Parasitism • The antagonistic micro organism parasitize the pathogen by coiling around the hyphae • Ex:Trichoderma - Pythium
- 11. Competition • The antagonistic microorganism compete with the pathogen for food and space making them unavailable for the pathogen.
- 14. Antibiosis The antibiotic compound(toxic metabolites) secreted by the biocontrol agent suppresses the growth of the pathogen. Eg: • P. fluorescens - Phenazine -1- carboxlic - suppress the wheat diseases. • Trichoderma spp - Trichodermin,gliotoxin and viridin.
- 15. Antibiosis
- 16. Lysis Different fungi and bacteria secrete hydrolytic enzymes degrade the cell wall of the pathogen. Eg : • Trichoderma sp.- β-1,3, glucanase and chitinases which degrade the chitins and glucans in cell wall and causes its lyses in R. solani
- 17. ISR/ SAR • Enhanced defensive capacity of the entire plant against pathogen • Mediated by jasmonic acid/ ethylene • Mediated by salicylic acid
- 18. Mass multiplication of Trichoderma viride • Sterilized molasses yeast medium • (Molasses 30g + yeast 5g + 1000ml of distilled water) • Trichoderma viride culture is inoculated into the medium • Incubated for 10 days - Mother culture • Medium is prepared in a fermentor and sterilized • Mother culture is added to the fermentor @ 1.5 liter/50 liters of medium • Incubate for 10 days
- 19. • Carrier substances sterilized at 20 p.s.i for 30 minutes for two successive days. • Carrier substances pH adjusted to 7 by adding CaCo3 @150g/kg. • Medium is mixed with carrier substrates viz., flyash, peatsoil, talc powder at 1:2 ratio • Mixture is air dried & mixed with Carboxyl Methyl Cellulose (CMC) @ 50g/kg of the product for sticking. • Packed in white polythene bags
- 21. Mass multiplication of Pseudomonas fluorescence • Sterilized King’s ‘B’ broth medium • Pseudomonas fluorescence inoculate in to the medium • Incubate for 72 hrs - Mother culture • Medium is prepared in a fermentor and sterilized • Mother culture is added to the fermentor @ 1 liter/100 liters of medium • Incubate for 72 hrs
- 22. • Carrier substances sterilized at 20 p.s.i for 30 minutes for two successive days. • Carrier substances pH adjusted to 7 by adding CaCo3 @150g/kg. • Medium is mixed with carrier substrates viz., flyash, peatsoil, talc powder at 1:2 ratio • Mixture is air dried & mixed with Carboxyl Methyl Cellulose (CMC) @ 50g/kg of the product for sticking. • Packed in white polythene bags
- 24. Mass multiplication of Bacillus subtilis • Sterilized King’s ‘B’ broth medium • A loopful of bacillus subtilis culture is inoculated to the medium, incubated for 24hrs. - Mother culture • Medium is prepared in a fermentor and sterilized • Mother culture is added to the fermentor @ 1 liter/100 liters of medium • Incubate for 72 hrs
- 25. • Carrier substances sterilized at 20 p.s.i for 30 minutes for two successive days. • Carrier substances pH adjusted to 7 by adding CaCo3 @150g/kg. • Medium is mixed with carrier substrates viz., flyash, peatsoil, talc powder at 1:2 ratio • Mixture is air dried & mixed with Carboxyl Methyl Cellulose (CMC) @ 50g/kg of the product for sticking. • Packed in white polythene bags
- 26. QUALITY CONTROL OF BIOCONTROL AGENTS: • Fresh product should contain 10-6 cfu/g (Trichoderma viride), 10-8 cfu/g (Pseudomonas fluorescence & Bacillus subtilis) • Maximum storage period is 120 days (Trichoderma viride) and 90days(Pseudomonas fluorescence & Bacillus subtilis) • After storage period at room temperature the population should be 10-6 cfu/g (Trichoderma viride), 10-7cfu/g (Pseudomonas fluorescence & Bacillus subtilis) • Size of the carrier substrate should be 50µ • Moisture content of the final product should not be more than 20%
- 27. Characteristics of good Bio-control agents • It should not be pathogenic to plants • It should have fast growth and sporulation • It should be amenable for mass multiplication • It should be compatible with bio fertilizer • It should not be toxic to human beings & animals • It should have more shelf life • It should not be toxic to beneficial organisms.