Various aspects of plant disease triangle. Where (A) No factor present, (B) Virulent pathogen is present but other two factors are absent, (C) Susceptible host exists but there is no pathogen and favoring environment, (D) Only favorable environment is prevailing but other two factors are lacking, (E) All three factors i.e. virulent pathogen, susceptible cultivar and conducive environment is existing at the same time. These conditions can lead towards PDE.