disease of rhizoctonia and fusarium root and rhizome rot of valerian medicinal plant in karaj

abstract valerian medicinal plant (valeriana officinalis) is a perennial succulent plant that is natural lenitive and good ingrained of diazepam. this study was conducted in order to identify the fungal agents of rhizome and root rot of valerian. infected plant samples that showed the symptoms of rotting and necrosis were collected from karaj and used in order to isolate disease agents. symptomatic samples were sterilized with sodium hypochlorite (1%) and cultured on pda medium in petri dishes. two fungal colonies grown from tissue segments and single hyphal tip or monoconidial isolates were obtained on pda medium followed by incubation in dark. the fungal isolate identified as rhizoctonia solani based on the following test. staining was done for hyphae of rhizoctonia isolate, number of nuclei in each cellule and hyphal diameter was determined. the hyphae contained several nuclei. single spore culture, were obtained from macroconidia of fusarium isolate. after 24 hours of incubation, single spores were transferred to selective medium, cla, for detection of fusarium isolates and also, were transferred to pda medium for sufficient mass production of spores and sporulation. after 7 days colonies appeared as white cream on top and cream at the bottom of petri plate with abundant micro and macro conidia. based on morphology and dimension of conidia and also, production of chlamydospore, the fungus was identified as fusarium solani. this is the first report of these fungi on v. officinalis in iran.