Background for this unit can be found on the Plant Disease Epidemiology Course produced by Phil A. Arneson (Cornell University) and published in the Web by the American Phytopathological Society. Several topics covered in this course and the most important concepts to be considered are listed below. Topics 1, 2, and especially 5 are very useful for this learning activity. Topics 3 and 4 are optional.

1. Plant disease epidemiology? Epidemic, epiphytotic, negative epidemic, endemic.

2. Disease progress. Linear disease progress, exponential disease progress, sigmoid.

2.1. The cyclical nature of plant disease. Infection cycle, monocyclic and polycyclic pathogens, monocyclic and polycyclic epidemics, polyetic epidemics.

2.2. Monocyclic epidemics. Examples.

2.3. Polycyclic epidemics. Examples.

2.4. Combinations of monocyclic and polycyclic epidemics. Examples.

3. Mathematical models.

3.1. Monocyclic inoculum production.

3.2. Polycyclic inoculum production.

4. Modelling disease progress.

4.1. Monocyclic disease progress. Monocyclic model of disease progress (linear model).

4.2. Polycyclic disease progress. Polycyclic model of disease progress (exponential model).

4.3. The upper limit to disease. Monocyclic model of disease progress adjusted for the limit to disease (monomolecular model) and polycyclic model of disease progress adjusted for the limit to disease (logistic model).

4.4. Estimating model parameters. Transformations for the monocyclic and polycyclic models.

4.4.1. Some examples. Logit.

4.4.2. Practical application.

5. Plant disease management strategies. Principles of disease management (avoidance, exclusion, eradication, protection, resistance, and therapy), plant disease control, plant disease management, strategy, tactic, monocyclic model (linear model), polycyclic model (exponential model), tactics for the reduction of (i) initial inoculum, (ii) infection rate, and (iii) duration of the epidemic.

5.1. Example.

5.2. Simulation. See an activity below.

5.3. Example.

6. Epidemiology references