VIEW ARTICLE

Disease Control and Pest Management

Fungicide Sensitivity and Genetics of IBP-Resistant Mutants of Pyricularia oryzae. M. Taga, Pesticide Research Institute, Kyoto University, Kyoto, 606, Japan; T. Waki(2), M. Tsuda(3), and A. Ueyama(4). (2)(3)(4)Pesticide Research Institute, Kyoto University, Kyoto, 606, Japan. Phytopathology 72:905-908. Accepted for publication 25 November 1981. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-905.

Mutants resistant to IBP (S-benzyl diisopropyl phosphorothiolate) were obtained from wild-type strains of Pyricularia oryzae isolated from finger millet. They were grouped in two classes, highly resistant (HR) and moderately resistant (MR). HR strains grew at 0.2 mM IBP and showed cross-resistance to isoprothiolane (diisopropyl 1,3-dithiolane-2-ylidenemalonate). In contrast, MR strains did not grow at 0.2 mM IBP, and were sensitive to isoprothiolane. The genetic nature of these strains was studied in crosses with sensitive strains. Random ascospore progenies from crosses with HR strains segregated 1:1 for resistance:sensitivity, indicating that a single major gene controls IBP-resistance in HR strains. Tests for allelism among HR strains indicated the existence of a common resistance locus designated as ibp. Data from crosses with MR strains suggested that MR is not controlled by a single factor.