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Canker
A plant canker is a small area of dead tissue, which grows slowly, often over years. Some cankers are of only minor consequence, but others are ultimately lethal and therefore can have major economic implications for agriculture and horticulture. Their causes include a wide range of organisms as fungi, bacteria, mycoplasmas and viruses. The majority of canker-causing organisms are bound to a unique host species or genus, but a few will attack other plants. Weather and animals can spread canker, thereby endangering areas that have only slight amount of canker. Although fungicides or bactericides can treat some cankers, often the only available treatment is to destroy the infected plant to contain the disease. Examples * Apple canker, caused by the fungus ''Neonectria galligena'' * Ash bacterial canker, now understood to be caused by the bacterium '' Pseudomonas savastanoi'', rather than ''Pseudomonas syringae''. After DNA-relatedness studies ''Pseudomonas savastanoi'' has bee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Citrus Canker
Citrus canker is a disease affecting ''Citrus'' species caused by the bacterium ''Xanthomonas'' (''X.axonopodis; X. campestris''). Infection causes lesions on the leaves, stems, and fruit of citrus trees, including lime, oranges, and grapefruit. While not harmful to humans, canker significantly affects the vitality of citrus trees, causing leaves and fruit to drop prematurely; a fruit infected with canker is safe to eat, but too unsightly to be sold. The disease, which is believed to have originated in Southeast Asia, is extremely persistent when it becomes established in an area. Citrus groves have been destroyed in attempts to eradicate the disease. Countries like Brazil and the United States also suffer from canker outbreaks. Biology ''Xanthomonas axonopodis'' is a rod-shaped Gram-negative bacterium with polar flagella. The bacterium has a genome length around 5 megabase pairs. A number of types of citrus canker diseases are caused by different pathovars and variants ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Butternut Canker
''Ophiognomonia clavigignenti-juglandacearum'' is a mitosporic fungus that causes the lethal disease of butternut trees (''Juglans cinerea''), butternut canker. It is also known to parasitize other members of the genus ''Juglans'' on occasion, and very rarely other related trees including hickories. The fungus is found throughout North America, occurring on up to 91% of butternut trees, and may be threatening the viability of butternut as a species. Distribution Butternut, the primary host of ''S. clavigignenti-juglandacearum'', is found in mixed hardwood forests throughout central North America, from New Brunswick to North Carolina. The pathogen was identified as an invasive species in 1967. It was first discovered in Wisconsin, but has since spread to other states and into Canada, making the Butternut an endangered species in Ontario. Its native origin is unknown, but possibly in Asia given the resistance of Asian walnuts to the disease. The United States Forest Service fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sirococcus Clavigignenti-juglandacearum
''Ophiognomonia clavigignenti-juglandacearum'' is a mitosporic fungus that causes the lethal disease of butternut trees (''Juglans cinerea''), butternut canker. It is also known to parasitize other members of the genus ''Juglans'' on occasion, and very rarely other related trees including hickories. The fungus is found throughout North America, occurring on up to 91% of butternut trees, and may be threatening the viability of butternut as a species. Distribution Butternut, the primary host of ''S. clavigignenti-juglandacearum'', is found in mixed hardwood forests throughout central North America, from New Brunswick to North Carolina. The pathogen was identified as an invasive species in 1967. It was first discovered in Wisconsin, but has since spread to other states and into Canada, making the Butternut an endangered species in Ontario. Its native origin is unknown, but possibly in Asia given the resistance of Asian walnuts to the disease. The United States Forest Service fou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cypress Canker
Cypress canker is a disease affecting ''Cupressus'' species, caused by one of several species of fungus in the genus ''Seiridium''. Infection causes die-back of twigs and branches in susceptible cypress trees, with rapidly increasing amounts of damage and the death of the tree. History The first epidemic of cypress canker was recorded in California in 1928, with Monterey cypress (''Cupressus macrocarpa'') being affected. Within a few years the local populations of this tree had been killed. The species is widely traded as an ornamental tree and the disease had soon spread worldwide, probably with nursery stock. Within five decades the disease had reached New Zealand, France, Chile, Italy, Argentina, Greece, most of Europe, Canada, North Africa, South Africa and Australia. The causal agent of this pandemic spread was the pathogenic fungus ''Seiridium cardinale'', with '' Seiridium cupressi'' and '' Seiridium unicorne'' sometimes being involved, but being less aggressive; other pat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bleeding Canker Of Horse Chestnut
Bleeding canker of horse chestnut is a common canker of horse chestnut trees (''Aesculus hippocastanum'', also known as conker trees) that is known to be caused by infection with several different pathogens. Infections by the gram-negative fluorescent bacterium ''Pseudomonas syringae'' pathovar ''aesculi'' are a new phenomenon, and have caused most of the bleeding cankers on horse chestnut that are now frequently seen in Britain. Disease cycle ''Pseudomonas syringae pv. Aesculi'' is a bacterium that causes bleeding canker of horse chestnut. The pathogen overwinters in the soil and can survive in the soil for about a year. It is spread by water, rain, and tools that were used on the infected tree. It causes lesions on the bark of the tree that can be near the base of the trunk or higher. The bleeding from the cankers mostly occurs in the spring and fall. Infection of the tree through lenticels and leaf scars when inoculated in a study occurred most readily in the spring and summe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neonectria Galligena
''Neonectria ditissima'' (syn. ''Neonectria galligena'') is a fungal plant pathogen. It causes cankers that can kill branches of trees by choking them off. Apple and beech trees are two susceptible species. Host range ''Neonectria ditissima'' host range encompass a variety of hardwood tree species such as, ''Fagus'', ''Populus'', ''Salix'', ''Betula'' and ''Acer'' species. These tree species population are present in both America and Europe. Phylogenetic studies have revealed genetic divergence among both populations, at specific loci (ß-tubulin, RPB2). However, due to high levels of within-population diversity of the American populations, it has been hypothesized that America is ''N. ditissima'' place of origin. Disease management ''Neonectria ditissima'' is a difficult pathogen to eradicate—but there are many ways to limit its spread and infection rate. Effective control requires a combination of cultural and chemical treatments. Cultural control Multiple cultural techniq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Butternut (tree)
''Juglans cinerea'', commonly known as butternut or white walnut,Snow, Charles Henry ''The Principal Species of Wood: Their Characteristic Properties'' 2nd ed. New York: John Wiley & Sons, 1908. p. 56. is a species of walnut native to the eastern United States and southeast Canada. Distribution The distribution range of ''J. cinerea'' extends east to New Brunswick, and from southern Quebec west to Minnesota, south to northern Alabama and southwest to northern Arkansas. It is absent from most of the Southern United States. The species also proliferates at middle elevations (about above sea level) in the Columbia River basin, Pacific Northwest; as an off-site species. Trees with (over mature) class range diameter at breast height were noted in the Imnaha River drainage as late as January 26, 2015. Butternut favors a cooler climate than black walnut and its range does not extend into the Deep South. Its northern range extends into Wisconsin and Minnesota where the growing s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seiridium
''Lepteutypa'' is a genus of plant pathogens in the family Amphisphaeriaceae. First described by the Austrian mycologist Franz Petrak in 1923, the genus contains 10 species according to a 2008 estimate. The genus ''Lepteutypa'' is teleomorphic (reproducing sexually) and the corresponding anamorphic name, used to describe the asexual form, is ''Seiridium'' (formerly ''Coryneum''). For instance, the name ''Seiridium cupressi'' can still be used for the anamorphic form of that species, but now that it is known that a sexual stage exists, the name ''Lepteutypa cupressi'' should be preferred for the species as a whole. On the other hand, no sexual stage of species ''Seiridium cardinale'' is known, so that is its only name. ''Seiridium cardinale'' and ''L. cupressi'' are important to gardeners and foresters as they cause the devastating Cyprus canker disease of ''Cupressus'', ''Thuja ''Thuja'' ( ) is a genus of coniferous tree or shrub in the Cupressaceae (cypress family). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudomonas Syringae
''Pseudomonas syringae'' is a rod-shaped, Gram-negative bacterium with polar flagella. As a plant pathogen, it can infect a wide range of species, and exists as over 50 different pathovars, all of which are available to researchers from international culture collections such as the NCPPB, ICMP, and others. ''Pseudomonas syringae'' is a member of the genus ''Pseudomonas'', and based on 16S rRNA analysis, it has been placed in the ''P. syringae'' group. It is named after the lilac tree (''Syringa vulgaris''), from which it was first isolated. A phylogenomic analysis of 494 complete genomes from the entire ''Pseudomonas'' genus showed that ''P. syringae'' does not form a monophyletic species in the strict sense, but a wider evolutionary group that also included other species as well, such as ''P. avellanae'', ''P. savastanoi'', ''P. amygdali'', and ''P. cerasi''. ''Pseudomonas syringae'' tests negative for arginine dihydrolase and oxidase activity, and forms the polymer levan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geosmithia Putterillii
The foamy bark canker is a disease affecting oak trees in California caused by the fungus ''Geosmithia pallida'' and spread by the Western oak bark beetle ('' Pseudopityopthorus pubipennis''). This disease is only seen through the symbiosis of the bark beetles and the fungal pathogen. The bark beetles target oak trees and bore holes through the peridermal tissues, making tunnels within the phloem. The fungal spores are brought into these tunnels by the beetles and begin to colonize the damaged cells inside the tunnels. Symptoms of the developing fungus include wet discoloration seeping from the beetle entry holes as the fungus begins to consume phloem and likely other tissues. If bark is removed, necrosis of the phloem can be observed surrounding the entry hole(s). As the disease progresses, a reddish sap and foamy liquid oozes from entry holes, thus giving the disease the name foamy bark canker. Eventually, after the disease has progressed, the tree dies. This disease is import ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foamy Bark Canker
The foamy bark canker is a disease affecting oak trees in California caused by the fungus ''Geosmithia pallida'' and spread by the Western oak bark beetle ('' Pseudopityopthorus pubipennis''). This disease is only seen through the symbiosis of the bark beetles and the fungal pathogen. The bark beetles target oak trees and bore holes through the peridermal tissues, making tunnels within the phloem. The fungal spores are brought into these tunnels by the beetles and begin to colonize the damaged cells inside the tunnels. Symptoms of the developing fungus include wet discoloration seeping from the beetle entry holes as the fungus begins to consume phloem and likely other tissues. If bark is removed, necrosis of the phloem can be observed surrounding the entry hole(s). As the disease progresses, a reddish sap and foamy liquid oozes from entry holes, thus giving the disease the name foamy bark canker. Eventually, after the disease has progressed, the tree dies. This disease is import ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xanthomonas Axonopodis
''Xanthomonas'' (from greek: ''xanthos'' – “yellow”; ''monas'' – “entity”) is a genus of bacteria, many of which cause plant diseases. 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. Taxonomy The genus ''Xanthomonas'' has been subject of numerous taxonomic and phylogenetic studies and was first described as ''Bacterium vesicatorium'' as a pathogen of pepper and tomato in 1921. Dowson later reclassified the bacterium as ''Xanthomonas campestris'' and proposed the genus ''Xanthomonas''.''Xanthomonas'' was first described as a monotypic genus and further research resulted in the division into two groups, A and B. Later work using DNA:DNA hybridization has served as a framework for the general ''Xanthomonas'' species classification. Other tools, including multilocus sequence analysis and amplified fragment-length ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
