identification and pathogencity of fungi involved in root and crown rot of wheat in north khorasan province(northeast of iran)

abstract the root and foot rot of wheat is one of the important disease of wheat over the world. the root and foot rot of wheat observed more frequently in the resent years at khorasan province (northeast of iran). for investigation the causal agents, several samples were collected from wheat fields of north khorasan in 2007 and 2008. culture of diseased parts of plants on pda resulted. fusarium oxysporum, f.solani, bipolaris sorokiniana,phoma sp. coniothyrium cerealis, trichoderma virens (gliocladium virens), and periconia circinata. their pathogenesity were tested (except t. virens) on wheat (chamran variety) in greenhouse experiments using completely randomized design. the results showed that b. sorokiniana, p. circinata, c. cerealis, and phoma sp. are pathogenic on wheat and decreases the fresh and dry weight of roots and lower parts of stalk (p= %5). among them b. sorokiniana determined as the principle agent of disease. it was highly pathogenic in both: with and without water stress conditions. the fusarium species were not pathogenic and did not induce the diseases symptoms. the gaeumannomyces graminis var. tritici and f. graminearum which are generally considered as important causal agents of root and foot rot of wheat in many regions were not isolated from diseased samples. the results indicated that b. sorokiniana is the major and principle causes of common root rot of wheat in north khorasan and probably in other parts of big khorasan. this is the first report for this pathogen in the region. other pathogenic fungi included c.cerealis, p. circinata, and phoma sp. were also reported for first time as the causal agents of wheat root rot from iran. they may play an auxiliary or a complex role in root rot of wheat.