ABSTRACT
Any pathogen can cause disease under favourable conditions. Pathogen itself or its parts that are capable of causing disease when brought near a host is called inoculum. Fungal pathogens are diversified where the vegetative body, dormant mycelium, special reproductive structures, various types of asexual spores and sexual spores, serve as inocula. In phanerogamic parasites, seeds are the potential inocula. Seeds in the soil survive for longer period. In temperate zones, plant pathogens must be adapted for survival overwinters or oversummers, like the powdery mildew pathogen that attacks fall-seeded wheat. Enduring structures of plant pathogens may be as simple as conidia or as complex as perithecia. The ability to live saprophytically enables many plant pathogens to survive in the absence of growing susceptible plants. Certain plant pathogens survive between growing seasons as saprophytes in the dead tissues of susceptible plants.
