Identification of causing pathogens and associate of wheat root and crown rots in Gorgan regional

The causes root rot of wheat are different in different regions. Because of disease symptoms appear late, concealment of farmers and experts sight, exert enormous damage to the product. In this study, for three consecutive years (2009-2011) from infected plants in wheat Fields Gorgan area, at different growth stages were randomly sampled the distance of each 2 km. The samples were transported to the laboratory and the separation and purification of fungi was performed on WA, PDA and special culture media. The fungus was identified based on their morphological characteristics. After identification, pathogenicity of the isolates tested was done in a test tube with seedling test methods and test plants in plastic pots in the greenhouse. All data to determine the frequency and dominant isolates were stored in the refrigerator. Finally 16 species, including 12 species of fungi Fusarium spp. with 4 fungi included Bipolaris sorokiniana, Gaeumannomyces gamines, Alternaria tineus and solaniRhizoctonia were isolated with different frequency from the infected root and crown of wheat in this region. The determine of isolates frequency in different years, Fusarium culmorum¡ F. graminearum¡ F. pseudograminearum and Bipolaris sorokiniana fungi were introduced with the highest percent frequency as the dominant fungi in the infect wheat roots and crowns rot in different regions of Golestan province.