Pathogenicity Variations of Puccinia recondita f. sp. tritici and P. graminis f. sp. tritici in Wheat-Growing Areas of Mexico During 1988 and 1989. R. P. Singh, International Maize and Wheat Improvement Center (CIMMYT), Lisboa 27, Apdo. Postal 6-641, 06600, Mexico, D.F., Mexico. Plant Dis. 75:790-794. Accepted for publication 17 January 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-0790.

A survey of Puccinia recondita f. sp. tritici in Mexico during 1988 and 1989 indicated the presence of 23 pathotypes. In the Pacific region and Highland Plateau, pathotype TCB/TD predominated both years, followed by TBD/TM. The population was most variable in the eastern lowlands of Mexico to the Texas border. Predominating pathotypes isolated from the collections made from durum wheats and triticales were different from those on bread wheats. Two extra supplemental host sets are proposed for future use in Mexico. Only six pathotypes of P. graminis f. sp. tritici were identified.

Keyword(s): leaf rust, stem rust, Triticum aestivum.