Breeding of Vegetable, Spice and Tuber Crops

Plant quarantine

• The first legal restrictions to hinder the spread of disease were enacted against human disease.
• It was the notorious outbreak of bubonic plague, which swept through Europe during the 14th century that led the Venetian Republic to appoint three guardians of public health, to exclude infected and suspected ships and to make the first quarantine of infected areas in 1403.
• The term quarantine has been derived from latin words 'quaranta giorni meaning fourty.
• Travellers from the Levant and Egypt, where plague was endemic, were isolated in a detection hospital for 40 days.
• In its strict sense, plant quarantine refers to the holding of plants in isolation until they are believed to be healthy.
• The meaning of this term has been broadened, and plant quarantine is now taken to mean all aspects of the regulation of the movement of living plants, living plant parts or plant products between politically defined territories or ecologically distinct parts of them.
• Plant quarantine may be defined as the restriction imposed by duly constituted authorities on the production, movement and existence of plants or plant materials, or animals or animal products or any other article or material or normal activity of persons and is brought under regulation in order that the introduction or spread of a pest may be prevented or limited or in order that the pest already introduced may be controlled or to avoid losses that would otherwise occur through the damage done by the pest or through the continuing cost of their control.
• When plant pathogens are introduced into an area in which they did not previously exist, they are likely to cause much more catastrophic epidemics than do the existing pathogens.
• Some of the worst plant disease epidemics that have occurred through out the world, for example the downy mildew of grapes in Europe and the bacterial canker of citrus.
• It is extremely difficult to predict accurately whether an exotic organism will become established, and once established, become economically important.

Factors which affect entry and establishment of an organism are
• Hitchhiking potential compared with natural dispersal
• Ecological range of the pest as compared with ecological range of its host
• Weather
• Ease of colonization including reproductive potential, and
• Agricultural practices including pest management.