Classification of Fungicides based on mode of action

Protectant

As the name suggests, protectant fungicides are prophylactic in their behaviour. Fungicide which is effective only it applied prior to fungal infection is called a protectant.
eg. Sulphur
      zineb

Therapeutunt

Fungicide which is capable of eradicating a fungus after it has caused infection and there by curing the plant is called chemotherapeutunt
 eg. Carboxin. 
       Oxycarboxin 
       Aureofungin.

Eradicant

Eradicant are those which remove pathogenic fungi from an infection court (area of the host around a propagating unit of a fungus in which infection could possibly occur)
 eg. Organic mercurials,
       lime sulphur
       dodine