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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 important because of its detrimental effects on oak trees and its ability to spread to several new Californian counties in just a couple years. == Hosts and symptoms == Hosts associated with ''Geosmithia pallida'' include a number of tree species, including oak and other hardwoods, pine and spruce trees, depending on the beetle vector.〔Jankowiak, R. et al. "Association of "Geosmithia" fungi (Ascomycota: Hypocreales) with pine- and spruce-infesting bark beetles in Poland." "Fungal Ecology" 11 (2014): 71-79.〕 In this case, the western oak bark beetles target live oak trees of western United States. Beetles tend to attack stressed trees that are already weakened from drought or injury. Symptoms causing branch dieback and tree death also include a cinnamon-colored gum seeping from multiple beetle entry holes on the bole, followed by a prolific, cream-colored foamy liquid.〔Lynch, S.C. et al. ″First Report of "Geosmithia pallida" Causing Foamy Bark Canker, a New Disease on Coast Live Oak ("Quercus agrifolia") in Association with "Pseudopityophthorus pubipennis" in California." "Plant Disease" 98 (2014): 1276-1277.〕 These symptoms, as well as signs (entry holes, larvae, beetles) of bark beetles, are key factors in diagnosis. Necrosis of xylem and phloem tissues underneath bark can be observed. Common Symptoms:〔Lynch, Shannon, Paul Rugman-Jones, and Richard Stouthamer. "Pest Alert: Geosmithia Pallida and Western Oak Bark Beetle." Geosmithia Pallida and Western Oak Bark Beetle ( Pseudopityophthorus Pubipennis) (n.d.): n. pag. Eskalen Lab: Foamy Bark Canker Disease. University of California, Riverside. Web.〕 * Wet discoloration on bark * Phloem necrosis * Beetle entry holes * Reddish sap oozing from entry holes * Foamy liquid from entry holes 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Foamy bark canker」の詳細全文を読む スポンサード リンク
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