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Disease Note

Pathogenicity of Puccinia recondita f. sp. tritici in Northeast India and Nepal During 1982 and 1983. S. Nagarajan, S. K. Nayar, and P. Bahadur, Regional Station, IARI, Flowerdale, Simla-171002, India; L. M. Joshi, Division of Mycology and Plant Pathology, IARI, New Delhi; and S. Lohani, Agricultural Experiment Station, Khumaltar, Katmandu, Nepal. Plant Dis. 68:537, 1984. Accepted for publication 15 March 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-537g.

During 1982 and 1983, isolates of the wheat leaf rust pathogen Puccinia recondita Rob. ex Desm. f. sp. tritici were collected from Bihar, West Bengal, Assam, and other northeastern states of India and tested on wheat differentials.  Susceptibility of the wheat Lr genes against 669 isolates in 1982 was Lr10 (4), Lr15 (40), Lr20 (66), Lr1 (67), and Lr2a (67).  In 1983, 28 rust isolates infected wheats with Lr15 (19), Lr20 (21), Lr1 (24), and Lr2a (24).  The 57 isolates from Nepal in 1982 were pathogenic on Lr15 (41), Lr20 (44), Lr1 (53), and Lr2a (53).  In 1983, 13 isolates from Nepal attacked wheats with Lr15 (8), Lr20 (4), Lr1 (9), and Lr2a (9).  In both years, no isolates from Nepal were found to attack Lr10.  Wheats with genes Lr9, Lr19, Lr24, and Lr26 were immune to all isolates from India and Nepal in 1982 and 1983; differential lines with Lr3 and Lr2c were susceptible to all isolates.  As Nepal is the source of primary inoculum of rust for the plains of India, deployment of any of the immune genes or Lr10 is recommended.

Reference: Nagarajan, S., et al. Curr. Sci. 52:413, 1983.