Authors
D. V.
McVey
,
Research Plant Pathologist
, and
D. L.
Long
,
Plant Pathologist, Cereal Rust Laboratory, Agricultural Research Service, USDA, University of Minnesota, St. Paul 55108
, and
J. J.
Roberts
,
Research Plant Pathologist, Cereal Rust Research, Agricultural Research Service, USDA, Georgia Agricultural Experiment Station, Experiment 30212
ABSTRACT
Wheat stem rust overwintered in southern Louisiana, southern Texas, southwestern Georgia, northeastern Arkansas, and southwestern South Carolina in the winter of 1994-95. Wheat stem rust caused negligible yield losses in wheat in the United States. Races Pgt-TPMK and QCCJ made up 39 and 31% of all isolates, respectively. Race TPMK comprised 67% of isolates from farm fields. Race Pgt-QCCJ was most common from barley, making up 93% from 47 collections. Six collections from Hordeum jubatum yielded six isolates each of races QCCJ and QFCS, and one isolate of race TPMK. No virulence was found to wheat lines with genes Sr6, 9b, 13, 22, 24, 25, 26, 27, 29, 30, 31, 32, 33, 37, Gt, or Wdl-1. Oat stem rust overwintered in plots at Beeville and Temple, Texas, in a field near San Antonio, and in southern Louisiana. Yield losses due to oat stem rust in 1995 were negligible. Race NA-27, virulent to Pg-1, -2, -3, -4, and -8, was again the predominant race in the United States, comprising 82% of the 225 isolates from 80 collections. NA-5 and NA-16 were the two other races identified from the United States, comprising 11 and 19% of the isolates. Only race NA-29 was found in four collections from Mexico.
