RACES OF PUCCINIA-GRAMINIS IN THE UNITED-STATES DURING 1992

Wheat stem rust overwintered in southern and east central Texas, south ern Louisiana, and southeastern Alabama. Yield losses to stem rust of wheat were traces, but a 1% yield loss in barley occurred in North Dak ota. Race Pgt-QCCJ was the most common race, making up 50% of the 450 isolates from 170 collections. If only the 89 collections from wheat w ere considered, the most common races were Pgt-TPMK, QFCS, and QCCJ, c omprising 53, 21, and 16% of the isolates, respectively. Eighty percen t of the isolates of QCCJ were from cultivated barley, and 90% of all isolates from cultivated barley were race QCCJ. No virulence was found to wheat lines with ''single' genes Sr13, 22, 24, 25, 26, 27, 29, 30, 31, 32, 33, 37, Gt, or Wld-1. Oat stem rust overwintered in southern Texas and southern Louisiana. Yield losses in 1992 were negligible. Ra ce NA-27, virulent to Pg-1, -2, -3, -4, and -8 was again the predomina nt race in the United States comprising 90% of the 279 isolates from 9 6 collections. NA-16, NA-5, and NA-23 were the other races isolated, c omprising 7, 2, and 1% of the population, respectively. No virulence t o Pg-9, -13, -16, or -a was found in the 1992 oat stem rust population .