| Rice blast is a major yield constraint of the irrigated rice in the State of Tocantins, Brazil. The objective of this investigation was to study the phenotypic and genetic diversity within the pathogen population of Pyricularia grisea in samples collected from four individual farms of rice cultivar Metica-1, under epidemic conditions of leaf blast. A set of 87 isolates was tested on 32 rice genotypes including eight international differentials. Considering 80% similarity in virulence, two groups comprising a total of 81 isolates were recognized, independently of the farms from which they were collected. Eighty percent of the isolates pertained to pathotype ID-14, indicating high cultivar specificity and narrow diversity of virulence in the sample... |
