First outbreak of sugarcane smut in Australia.

Abstract

Sugarcane smut (Ustilago scitaminea) was identiJied for theJirst time in Australia in the Ord River Irrigation Area (ORIA), in the semi-arid tropics of Western Australia, in July 1998. Commercial sugarcane production began in the ORlA in 1995. The ORIA is about 1600 kin from sugarcane production areas along the eastern seaboard of Australia and 2500 km from Java, where high levels of smut are known to occur. In surveys up to October 1998, smut was found on nine farms; however, the main concentration of the disease was initially on one farm. The two most severely irzfected crops (about 600 andh250 infectedplants/ha) were planted from uninfected sources in September 1996 and May 1997 respectively, indicating a rapid build-up of the disease in the hot, dry climate of this area. Spread in planting material and by wind within the ORIA occurred during 1998. It is most likely that sugarcane smut entered Australia as windborne spores, probably from Indonesia. Surveys in eastern Australia have found no evidence of the disease.