Question

classify crop disease on basis of the mode of occurrence and write one example of each​

Answer 1

Answer:

There is nothing about crop disease

Explanation:

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Classification of Plant Diseases | Botany

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In this article we will discuss about the classification of plant diseases.

(i) Diseases classified in relation to their occurrence:

Study of plant dis­eases in relation to their occurrence (interaction of populations of plants, pathogens and environment) is known as epidemiology. There may be infectious disease and contagious disease. A disease which spreads slowly and is incited by a transmissible pathogen is referred as infectious disease, and that which spreads rapidly is a contagious disease

Considering from the point of view of occurrence the diseases are often classified as:

Endemic, epidemic or epiphytotic, and sporadic.

A disease which constantly occurs from year to year in moderate to severe form is an endemic disease. Greeneria fruit rot of grape (Vitis vinifera) is an endemic disease in India caused by Greeneria uvicola. But an epidemic disease or epiphytotic disease is the one whose incidence is periodical in wide areas spreading very fast. The term epi­phytotic is rather used in case of plant disease.

The epiphytotic disease is usually very responsive to variations of environmental conditions which actually control its incidence. Like endemic disease, the pathogen may be more or less constantly present but to ensure disease development environmental conditions must be favourable.

Diseases are often classified as: soil-borne disease, seed-borne disease, wind-borne disease, etc. Here importance is given only on the dispersal medium of the pathogen and nothing else.

(iii) Diseases classified according to parts of host affected:

(c) Diseases resulting in the overgrowth or over development of the plants or organs affected-hypertrophic.

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