Wheat leaf rust was detected in WA crops in July 1997. Although more widespread in WA in recent years, the disease was not a major concern in the state prior to 1990.
Assuming no significant change in the environment, this suggested either a more aggressive pathogen or more susceptible varieties.
Investigations have suggested a more aggressive pathotype. Samples of leaf rust collected in the Esperance district in 1990 were of a pathotype not previously reported from WA.
This pathotype spread throughout the WA wheat belt and reached epidemic levels in 1992 with yield losses of 10-20 per cent in moderately susceptible to very susceptible varieties. More than 100,000 hectares were sprayed with fungicide in that year.
Studies at the University of Sydney Plant Breeding Institute Cobbitty indicated that the paihotype detected in WA in 1990 originated from the eastern wheat belt, where it had been common.
Researchers believed it originated from outside Australia. This and a related pathotype are now the most common leaf rusts isolated in annual surveys conducted at PBI Cobbitty.
Movement of rust pathotypes from the eastern to western Australian wheat belts, as detected in 1990, provides a timely reminder that wheat stripe rust will one day reach the west.
Contact: Robert Parks 02 4655 0806