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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 ]
Plant disease triangle. Epidemiology is the study of factors affecting the outbreak and spread of infectious diseases. [11] A disease triangle describes the basic factors required for plant diseases. These are the host plant, the pathogen, and the environment. Any one of these can be modified to control a disease. [12]
Child with congenital heart disease with central cyanosis that is worsened by measles. Note the bluish-purple discoloration of the fingernails, lips, eyelids, and nose, along with prominent nail clubbing. Central cyanosis may be due to the following causes: Central nervous system (impairing normal ventilation): [5] Intracranial hemorrhage
A leaf spot is a limited, discoloured, diseased area of a leaf that is caused by fungal, bacterial or viral plant diseases, or by injuries from nematodes, insects, environmental factors, toxicity or herbicides. These discoloured spots or lesions often have a centre of necrosis (cell death). [1]
Citrus blight, caused by an unknown agent, infects all citrus scions. Fire blight of pome fruits, caused by the bacterium Erwinia amylovora (Burrill) Winslow et al., is the most severe disease of pear and also is found in apple and raspberry, among others. Bacterial leaf blight of rice, caused by the bacterium Xanthomonas oryzae (Uyeda ...
Chondrostereum purpureum is a fungal plant pathogen which causes Silver leaf disease of trees. It attacks most species of the rose family Rosaceae, particularly the genus Prunus. The disease is progressive and often fatal. The common name is taken from the progressive silvering of leaves on affected branches.
Xanthomonas (from greek: xanthos – "yellow"; monas – "entity") is a genus of bacteria, many of which cause plant diseases. [1] There are at least 27 plant associated Xanthomonas spp., that all together infect at least 400 plant species. Different species typically have specific host and/or tissue range and colonization strategies.
This is the epiphyte phase of P. syringae’s life cycle where it will multiply and spread but will not cause a disease. Once it enters the plant through a leaf's stomata or necrotic spots on either leaves or woody tissue then the disease will start. [17] The pathogen will then exploit and grow in intercellular space causing the leaf spots and ...