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In epidemiology, force of infection (denoted ) is the rate at which susceptible individuals acquire an infectious disease. [1] Because it takes account of susceptibility it can be used to compare the rate of transmission between different groups of the population for the same infectious disease, or even between different infectious diseases.
Plant diseases are diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). [1] Organisms that cause infectious disease include fungi , oomycetes , bacteria , viruses , viroids , virus -like organisms, phytoplasmas , protozoa , nematodes and parasitic plants . [ 2 ]
Instead, it forces the infected plant to grow clusters of leaves into brilliant yellow "pseudoflowers" bearing the fungal spermatogonia. Insects visiting the pseudoflowers transfer spermatia from one host plant to another, in the same way that pollinators transfer pollen between the true flowers of uninfected plants.
Plants can show many signs or physical evidence of fungal, viral or bacterial infections. This can range from rusts or molds to not showing anything at all when a pathogen invades the plant (occurs in some viral diseases in plants). [9] Symptoms which are visible effects of diseases on the plant consist of changes in color, shape or function. [9]
Plant disease resistance is the ability of a plant to prevent and terminate infections from plant pathogens. Structures that help plants prevent pathogens from entering are the cuticular layer, cell walls, and stomata guard cells.
A plant line with acceptable resistance against one pathogen may lack resistance against others. Breeding for resistance typically includes: Identification of plants that may be less desirable in other ways, but which carry a useful disease resistance trait, including wild plant lines that often express enhanced resistance.
Hypersensitive response (HR) is a mechanism used by plants to prevent the spread of infection by microbial pathogens.HR is characterized by the rapid death of cells in the local region surrounding an infection and it serves to restrict the growth and spread of pathogens to other parts of the plant.
Given the lack of knowledge of human infectious diseases at this time (and well into the 19th century) this was not an unusual conclusion, [15] but what is surprising is that while tulip mosaic disease has a far more impressive and documented history than any other plant virus, the realization that it was a communicable plant disease, let alone ...