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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 ]
Life cycle of the black rot pathogen, the gram negative bacterium Xanthomonas campestris pathovar campestris. Plant pathology or phytopathology is the scientific study of plant diseases caused by pathogens (infectious organisms) and environmental conditions (physiological factors). [1]
VHS disease in a gizzard shad. Viral hemorrhagic septicemia (VHS) is a deadly infectious fish disease caused by Viral hemorrhagic septicemia virus. It afflicts over 50 species of freshwater and marine fish in several parts of the Northern Hemisphere. [1] Different strains of the virus occur in different regions, and affect different species.
The chosen insect vector of a plant virus will often be the determining factor in that virus's host range: it can only infect plants that the insect vector feeds upon. This was shown in part when the old world white fly made it to the United States, where it transferred many plant viruses into new hosts. Depending on the way they are ...
The symptoms appeared on plants onto which pieces from affected plants had been budded—indicating that the disease was caused by a transmissible pathogenic agent. A fungus or bacterium could not be found consistently associated with symptom-bearing plants, however, and therefore, it was assumed the disease was caused by a virus. Despite ...
Rickettsia causes diseases in animals, such as typhus and spotted fever, [2] as well as in other plants, such as phony disease of peach and almond leaf scorch. [3] Papaya Bunchy Top is found throughout the American tropics and has been economically important due to its major impact on fruit production. [ 4 ]
Sporotrichosis is caused by fungi of the S. schenckii species complex. [5] [6] Because S. schenckii is naturally found in soil, hay, sphagnum moss, and plants, it most often affects farmers, gardeners, and agricultural workers. [7] It enters through small cuts in the skin to cause a fungal infection. [1]
Leaf spots are visible symptoms of virus infections on plants, and are referred to as systemic symptoms. [7] In systematic virus infections leaf spots caused by viruses show a loss of green colour in leaves, due to chlorosis which is a repression of chlorophyll development. [1]