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''Phialophora gregata'' is an Deuteromycete〔Weidong, Chen, Lynn E. Gray, James Kurle, and Craig Grau. "Specific Detection of Phialophora Gregata and Plectosporium Tabacinum in Infected Soybean Plants Using Polymerase Chain Reaction." Molecular Ecology 8.5 (1999): 871-77. Web.〕 fungus that is a plant pathogen which causes the disease commonly known as "brown stem rot of soybean. ''P. gregata'' does not produce survival structures, but has the ability to overwinter as mycelium in decaying soybean residue.〔 Two strains of the fungus exist;〔Grau, C. "Brown Stemrot of Soybeans." There are many ways to manage Phialophora gregata. The most effective form of management is disease resistance,〔 but crop rotation, tiliage, SCN management, and changing the pH of the soil can also be effective 〔〔Robertson, A.E. and Nutter, F.W. Iowa Soybean Disease Survey. www.soybeandiseasesurvey.info〕 ==Symptoms and Signs== ''Phialophora gregata’''s infection of a soybean plant is accompanied by browning of the plant’s vascular and pith tissues.〔 The plant often exhibits chlorosis and necrosis, as well as leaf browning.〔 Wilting and defoliation are also known to occur.〔 Signs of infection often go unnoticed until reproductive stages of a plant’s life cycle. They can be diagnosed earlier on by opening the stem and visualizing the pathogen. One can visualize signs by cutting open the stem in early stages of infection,〔 but symptoms do not become apparent until after the soybean pod formation.〔Monsanto. "Brown Stem Rot and Sudden Death Syndrome in Soybean." Lewis Hybrids. Lewis Hybrids, 2010. Web. Depending on which strain infects the plant, and what the environmental conditions are,〔Westphal, Andreas, Scott Abney, and Gregory Shaner. "Diseases of Soybean: Brown Stem Rot." Purdue University Department of Botany and Plant Pathology and USDA-ARS, May 2006. Web.〕 the effect is more or less potent. Genotype A causes browning of stems as well as foliar symptoms such as interveinal chlorosis, defoliation and wilting.〔〔 Robertson, A. & Tabor, G. “Soybean Brown Stem Rot.” Iowa State University. Secondary symptoms of brown stem rot are stunting, premature death, decrease in seed number, reduced pod set, and decrease in seed size.〔 Disease from ''P. gregata'' is easily confused with ''Fusarium'' wilt, due to the similar vascular symptoms observed in both.〔Smith, S. N. "Association of Phialophora Gregata with Fusarium Solani F. Sp. Pisi in Garbanzo Beans in California." APS Net 83.9 (1999): 876.1. Web.〕 The diseases could be differentiated through growth on isolation media.〔 The two diseases can be further distinguished by splitting the stems. A split stem with ''Fusarium'' infection would have tan or light brown discoloration in the cortex and a normal white pith, while a split stem with ''P. gregata'' would have a discolored, reddish brown pith.〔 Root rot and blue masses of spores are symptoms only caused by ''Fusarium''.〔 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「Phialophora gregata」の詳細全文を読む スポンサード リンク
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