PATHOGENIC SPECIALIZATION OF PUCCINIA-GRAMINIS ON WINTER CEREALS AND GRASSES IN AUSTRALIA IN 1990 AND 1991

Levels of stem rust on wheat, triticale, barley, rye and grasses were low during 1990 and 1991. In 1990, 46 samples of stem rust were receiv ed, from which 49 isolates were pathotyped. The Satu triticale pathoty pe 34-2,12,13 was most commonly isolated from samples collected in Que ensland and northern New South Wales, while in southern New South Wale s and Victoria and in South Australia the Oxley pathotype 343-1,2,3,5, 6 was most prevalent. Pathotype 343-1,2,3,5,6,8,9, virulent on Festigu ay (Sr30), was isolated at a low frequency in Victoria and South Austr alia. In Western Australia, the Oxley pathotype and an older pathotype , 34-2, were isolated frequently. Only one of the ten samples of stem rust collected in 1991 came from a commercial crop. This sample origin ated from barley and was identified as the non-wheat attacking 'scabru m' form of stem rust. Most (seven) samples came from Queensland, from which seven isolates of pathotype 343-1,2,3,5,6 and two of pathotype 3 4-2,12,13 were recovered. The remaining samples yielded single isolate s of pathotypes 34-2,7,12,13 (northern New South Wales) and 343-1,2,3, 5,6 (southern New South Wales and South Australia). The Festiguay path otype 343-1,2,3,5,6,8,9 was not isolated during the 1991 survey period . Virulence was not detected for Sr22, Sr24, Sr26, Sr31, Sr32 or Sr35 during the 1990 and 1991 survey periods.