The wet summer and autumn period has provided favourable conditions for rust survival in the lead-up to the 2022 season in eastern Australia.

The Plant Breeding Institute (PBI) has already received early reports of stripe rust in wheat at the time of writing (20 May) at Temora, Canowindra and Wallendbeen in New South Wales.

Stripe rust of wheat first appeared in Australia in 1979. Since then, it has managed to survive the hot summer months and reappear any time from mid-May to the end of September. The average date on which stripe rust has first been detected in eastern Australia between 1979 and 2021 is 23 July.

Date of first detection

While the development of stripe rust in a given season depends on many factors, PBI’s long-term data shows that the date of first detection is often a good predictor of epidemic potential; earlier detection generally means more stripe rust. For example, the first detection on 25 May in 2021 was followed by significant amounts of stripe rust in wheat crops in eastern Australia that year.

Its early detection in 2022 suggests that we could again see significant pressure from stripe rust disease in wheat crops across eastern Australia this year should the wet conditions that favour rust development continue. The Bureau of Meteorology has predicted above-median winter rainfall for much of Australia.

PBI has also received reports of crown rust of oats in northern NSW. Inspections in the grain growing regions of Victoria and NSW in late March showed the common occurrence of crown rust and stem rust in pockets of roadside wild oats in Victoria and southern NSW.

Monitoring is crucial

The early occurrence of rust in wheat, barley and wild oats highlights the importance of monitoring for the presence of rust in all cereal crops over the coming months. The PBI urges growers to also inspect nearby weedy grasses for rust, especially stripe rust on barley grass.

As reported in the last edition of Ground Cover (issue 158, May-June 2022), a new pathotype of the barley grass stripe rust pathogen with increased virulence on barley was detected in 2021. Although this new pathotype is not expected to cause damage in cereal crops, it was widespread on barley grass in eastern Australia 2021 and it could change again to become more virulent on barley, meaning that ongoing monitoring is critical.

Growers are reminded to send freshly collected samples in paper only to the Australian Cereal Rust Survey, University of Sydney, Australian Rust Survey, Reply Paid 88076, Narellan, NSW, 2567.

More information: Robert Park, 02 9351 8806, robert.park@sydney.edu.au; Interactive map showing distribution of rust pathotypes.