Morphological and Cytologic Studies of Two Isolates of Pyricularia oryzae in Relation to Their Pathogenic Variability on Rice. R. A. Singh, Senior Research Fellow, Plant Pathology Department, International Rice Research Institute, P.O. Box 933, Manila, Philippines. K. V. S. R. K. Row, Postdoctoral Fellow, F. L. Nuque, Assistant Scientist, and J. P. Crill, Head, Plant Pathology Department, International Rice Research Institute, P.O. Box 933, Manila, Philippines. Plant Dis. 67:603-605. Accepted for publication 9 November 1982. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-603.

The morphological, cytologic, and pathogenic behavior of isolates T63 and P2017 of Pyricularia oryzae on rice (Oryza sativa) showed the former as stable and the latter as an unstable isolate. Studies showed that it was feasible to select a stable isolate on the basis of morphologic-like colony characters, absence or presence of intertwining hyphae, anastomosis, and nuclear condition of hyphae that provide complementary information in addition to pathogenic patterns on test cultivars.