Diversity of Virulence Within and Among Populations ofPuccinia reconditaf. sp.triticiin Different Areas of the United States

Data from surveys of pathogenic races of Puccinia recondita f. sp. tritici from 1988 to 1990 were analyzed to compare phenotypic diversity within and among pathogen populations in eight areas of the United States. Collections from nurseries were significantly more diverse than those from commercial fields in five of seven areas. Populations from the southern, central, and northern Great Plains were phenotypically similar. The population from California and other southwestern states was distinctly different from populations from all other areas(.)