Identification of new fungi isolated from Echinochloa spp., as potential biological control agents in paddy fields in Iran

Abstract

Echinochloa spp. are the most important weeds of rice. Fungal pathogens can be exploited as biological agents for the management of agricultural weeds. Two pathogenic fungal species were isolated from naturally infected Echinochloaspecies and identified. In order to isolate the fungus from disease tissues, the obtained samples were cultured on potato dextrose agar medium. Isolates were cultured due to sporulation on water agar medium. Morphological characters of isolates were studied in order to identify the taxonomy. According to the results, isolates belonged to Bipolaris maydis (Nisikado and Miyake) Shoem., and Bipolaris australiensis (Tsuda and Ueyama) Alcorn. Pathogenicity test of isolates in species was done in desiccators, and revealed the pathogenicity of the species and their ability to cause leaf blight on Echinochloa spp.. Inoculation was done using a spore suspension consisting of 105 spore/ml distilled water and 1%Tween-20 at the 2 to 3 leaf stage. Results indicated that the disease rating caused by B. maydis and B. australiensis in Echinochloa spp. was higher than that observed in the studied rice cultivar. Hence B. maydis and B. australiensis can be considered as a probable mycoherbicide for controlling Echinochloa species. Key words: Echinochloa spp., fungi, biological control, Bipolaris spp.