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Resistan is a mechanistic simulation model of the process of selection of fungicide-resistant biotypes of a hypothetical fungal pathogen of a hypothetical crop.

The fungus is a polycyclic organism with many generations per season. There is no genetic component in this simulator. Reproduction is assumed to be asexual. A small proportion of the initial inoculum is designated as the fungicide-resistant biotype at the start of the season, and the response of that population to various fungicide spray programs is observed as the season progresses.

Resistan can be made to simulate different fungi and different fungicides by changing the parameters that control the model.

One interesting feature of this simulation is the ability to include economic factors in the simulation. Total costs, total revenue, and profit are calculated at the end of each season based on the following parameters:

  • Fungicide Cost is used in the benefit-cost analysis at the end of the simulation.
  • Application Cost is the cost of a single spray application in dollars per acre. This does not include the cost of the fungicide.
  • Fixed Costs are the total crop production costs, excluding the fungicide spray application cost and the cost of the fungicides.
  • Maximum Revenue is the expected revenue from the crop without any losses resulting from the disease.