technology in agriculture

Diseases in plants can be caused by a number of pathogens and almost all plant species. Therefore, it is difficult to classify plant disease based on one factor only. So p lant diseases can be classified in many ways based on the factors involved in the disease inciting (viz., susceptible host, parasite and environment). Plant diseases can be classified as; Leaf yellowing of Malvastrum sp. (viral disease) i) On the basis of Causal Organisms For example,  Diseases caused by bacteria, Diseases caused by viruses, Diseases caused by mollicutes, Diseases caused by fungi ii) On the basis of the Type of Plants For example; Cereal crop diseases, Diseases of fruit crops, Diseases of vegetable crops, Diseases of ornamental plants iii) On the basis of their Symptoms For example; Rusts, Smuts, Powdery Mildews, Downy Mildews, Leaf blights, Vascular wilts, Damping off, Leaf blights iv) On the basis of their Occurrence a) Endemic Diseases The disease which is present in more or less constantly...

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...