Disease Note

Evidence for Local Source of Puccinia recondita on Wheat in Pennsylvania. J. F. Schafer, USDA-ARS, Cereal Rust Laboratory, University of Minnesota, St. Paul 55108. D. L. Long, USDA-ARS, Cereal Rust Laboratory, University of Minnesota, St. Paul 55108. Plant Dis. 70:892. Accepted for publication 13 May 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-892b.

Puccinia recondita Rob. ex Desm. f. sp. tritici, causal agent of leaf rust of Triticum spp., is believed to overwinter some years in much of the winter wheat area of North America. Specific data, however, are limited. During 8 yr (1978–1985) of race monitoring in the United States, only 25 isolates of race UN 11 (1) with a phenotype of p 1, 17 or p 1, 17, 18 were obtained among a total of 3,935. Of the 25 isolates, 23 were collected in four counties in central Pennsylvania during 1983 (1) and 1985. The 23 occurred among 99 isolates collected from Pennsylvania during those 2 yr, compared with only 37 collected during the other 6 yr combined. The 23 isolates thus appear to represent a local, rather rare leaf rust population in Pennsylvania observed in years of greater total local sampling. The near uniqueness of these 23 to the area implies a source within this area and thus provides circumstantial evidence for local oversummering and overwintering of these phenotypes, although not in detectable quantity every year.