Survey, Collection, Isolation and Identification of Isolates of Pyricularia Oryzae Causing Rice Blast in Southern Karnataka by using Host Differential Lines

A survey was conducted during kharif 2015-16 in southern Karnataka, to assess the percent severity and incidence of rice leaf and neck blast. The freshly infected leaves were randomly collected from all the talks viz., Mandya, Maddur, Nagamangala, Shrirangapattana, Pandavapura, Krishnarajpet, and Malavalli of Mandya district of Karnataka, from these samples, the causal organism was isolated by following tissue isolation method and monoconidial isolation. Among all the talk, the highest percent disease severity of the rice leaf blast was recorded (38.92%) in Krishnarajpet Taluk and lowest incidence was recorded (27.39%) in Maddur Taluk. Among all the talk, the highest percent disease incidence of neck blast was recorded (20.61%) in Shrirangapattana Taluk and lowest incidence was recorded (13.04%) in Maddur Taluk. Screening of promising host differential lines against rice blast was carried out to identify the races of P. oryzae. Among twenty five host differential lines of paddy, 2, 3, 4, 10, 12, 13 and 22 host differential shows resistant reaction. Host differential lines 6, 7, 8, 9, 11, 14, 23, 24 and 25 show moderate resistances. Host differential lines 15, 16 and 17 exhibited susceptible reaction.