Vol. 11, Issue 5 (2022)

Author(s):
AC Murudkar, JJ Kadam, PA Sahane, MS Dhumal and VP Kharbadkar

Abstract:
Rice leaf scald disease, caused by the fungal pathogen Microdochium oryzae, is worldwide important disease of rice (Oryza sativa L.). The disease has been reported to causes yield losses of up to 23.4% in India. Hence, in this study, morphological and cultural studies were done to understand the pathogen behaviour. The results revealed that M. oryzae produced white to off white, fluffy, cottony, septate mycelial growth which later turned to dull white with deep orange or salmon or pink colored droplets of conidial masses. Mycelium was hyaline, septate, irregularly branched and breadth measured 1.89 to 6.09 µm (Ave. 4.15 µm). Conidia were hyaline, bicelled, without constriction at septum, oval to oblong, slightly curved, tapering at both ends and deep orange or salmon coloured when in mass and measured 9-13 µm × 3-4 µm in size. Among the seven different culture media evaluated, potato dextrose agar medium and carrot agar medium were found most suitable and were significantly superior over rest of media and encouraged maximum radial mycelial growth (90mm) of M. oryzae. Mycelial growth of test fungus on carrot agar medium was maximum (90mm) but it was sparse, whereas on host leaf extract agar medium fungal sporulation was fair. Asthana and Hawker’s agar and carrot agar medium were poor in the conidia formation.