Epiphytology or Epidemiology:
- It is a study of the rate of multiplication of a pathogen and spread of the disease caused by it in a plant population.
- Epidemiology deals with outbreaks and spread of diseases in a population
Importance of epidemiology:
Knowledge of epidemiology is useful in forecasting of a disease and also for the
management of a disease.
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Compound interest disease/ polycyclic |
Simple interest disease/Monocyclic |
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Rate of increase of disease is mathematically analogous to compound interest in money (Interest is added periodically to the capital; interest gets interest) |
Rate of increase of disease is mathematically analogous to simple interest in money (Interest is added only at the end; interest does not get interest) |
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Pathogen produces spores at rapid rate |
Pathogen produces spores at very slow rate |
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Propagules disseminate by air |
Propagules disseminate by soil or seed |
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Incubation period and sporulation period is short |
Incubation period and sporulation period is long |
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There are several generations of the pathogen in the life of a crop |
There is only one generation of the pathogen in the life of a crop |
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Ex: Rusts of cereals |
Ex: Smuts of wheat, barley & sorghum |
Disease Triangle:
- The interactions of three components of disease, i.e., the host, pathogen and environment, can be visualized as a disease triangle.
Fig : Disease triangle
- The interaction of susceptible host plant, virulent pathogen and favourable environmental conditions leads to the development of the disease.
Disease Pyramid:
- The disease triangle can be expanded to include two more components, time and humans.
- The amount of each of the three components of disease and their interaction in the development of the disease are affected by fourth component, time.
- Thus addition of time component to the disease triangle results into a tetrahedron or disease pyramid.