fungi associated with root and crown rot of wheat in khuzestan province, iran

to identify the fungi associated with foot and root rot of wheat in the khuzestan province, diseased samples were collected at all growth stages in three growing seasons of 2004-2007. pieces of infected parts of the root and foot were surface sterilized and cultured on acidic and non acidic pda media. one hundred and fifteen isolates were obtained and on the basis of macroscopic and microscopic characters and valid keys were identified as fusarium solani, f. equiseti, f. moniliforme, f. subglutinans, f. sambucinum, f. culmorum, f. proliferatum, f. pseudograminearum, f. longipes, f. avenacium, f. nygamai, f. semitectum, f. lateritium, rhizoctonia solani, bipolaris sorokiniana and pythium sp. f. equiseti, f. solani and f. culmorum with occurrence frequencies of 16.07, 16.07 and 12.5 % respectively were more frequent than all other species. results of pathogenicity tests indicated that f. pseudograminearum and f.culmorum were the main fungi associated with wheat root and crown rot disease in khuzestan while other fusarium spp. such as f. equiseti are probably aggravated by moisture stress at different growth stages of crop due to poor irrigation management. rhizoctonia solani with occurrence frequency of 8.03 % in some regions such as ahvaz, shoush, shoushtar and baghmalek was important agent of crown and root rot of wheat second to fusarium species. bipolaris sorokiniana and pythium sp also caused crown and root rot but with less frequency percent.