1Directorate of Rice Research, Rajendranagar, Hyderabad-30, Andhra Pradesh, India.
Department of Plant Pathology, Acharya N.G. Ranga Agricultural University, Rajendranagar, Hyderabad-30. Andhra Pradesh, India.
* Part of Ph.D. thesis submitted by first author to Acharya NG Ranga Agricultural University Present Address: Regional Agricultural Research Station, Palem - 505 215, Andhra Pradesh, India.