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In this article we will discuss about the principle, requirements and procedure for isolation of plant pathogens.
Principle:
A medium with a carbon source and inorganic salts will permit the growth of plant pathogens which can be maintained on agar slants of the same medium.
Requirements:
1. Infected plant parts, leaves/stem infected with Alternaria.
2. Potato Dextrose agar with strepto-penicillin.
3. Petri plates with moist filter paper.
4. 1% sodium hypochlorite or 0.1% HgCl2.
5. Sterile Petri plates.
6. Sterile distilled water.
7. Scalpel/blade.
8. Bunsen flame.
9. Alcohol 95%.
Procedure:
1. Excise infected part along with some uninfected region using sterile scalpel and keep this in a sterile Petri plate with 0.1% HgCl2 for 2-3 minutes.
2. Wash 3-4 times with sterile distilled water, blot dry on sterile filter paper and transfer this after cutting into bits (across infected region) to PDA plates and gently press them on to the agar. Incubate at room temperature (28°-30°C) for 72- 120 hour (3-5 days). Observe growth and transfer mycelium and spores to agar slants of the same medium for identification and further use. Bacteria; Plant pathogenic bacteria can also be isolated on PDA in the same way.