Plant Disease Inciting Agents
The plants in nature are exposed to a number of parasites and pathogens. The distinction of parasite and pathogen must be very clear in mind before distinguishing disease causing organisms from other micro organisms living on and getting nutrition from the host. Grass smut grown on MEA medium The surface of plant is vulnerable to both disease causing pathogens and other environmental conditions. But the pathogens can be classified into one of the following groups. i) Biotic Agents (Bacteria, Mollicutes, Fungi, Algae, Nematodes, Mycoplasmas etc) ii) Abiotic agents (Environmental factors like Temperature, Rainfall, Humidity, High or low pH etc) iii) Mesobiotic agents (These are Viruses and Viroids) 1 . BIOTIC AGENTS A) FUNGI Alternaria sp. Fungi are small, generally microscopic, eukaryotic, usually filamentous, branched, spore-bearing organisms that lack chlorophyll. Fungi have cell walls that contain chitin and glucans (but no cellulose) as the skeletal comp...