The University of Sydney’s specialist cereal rust research team has released preliminary data from its studies of the current stripe rust outbreak to help growers decide what varieties to retain and store as next year’s seed.

The team has ranked the responses it expects in 2004 from New South Wales wheat varieties exposed to two strains of stripe rust – the one known in eastern Australia for a number of years for its effect on the variety H45 and the newly identified one from Western Australia (WA).

Col Wellings, senior rust pathologist at the university’s Plant Breeding Institute (PBI) at  Cobbitty, says even though the results are preliminary, and require further tests for confirmation, they will help growers with their seed retention decisions.

Dr Wellings, who is on secondment from NSW Agriculture to the University of Sydney, says seasonal conditions this year contributed to the most severe stripe rust outbreak for two decades in eastern Australia.

The season also saw the first occurrence in the east of the new stripe rust strain that hit Western Australian last year, and this resulted in many wheat varieties showing less than expected resistance to the disease, 

“While we are releasing our preliminary data to provide a basis for expected disease responses next year, a variety’s response will depend on many factors, including the strain of rust occurring at a particular location,” Dr Wellings said.

“We’ve ranked the responses of NSW varieties to both the WA strain and the one associated with the variety H45 (110 E143A+) and, while it is difficult to predict yield losses, it would be reasonable to expect that varieties with rankings of five or less will sustain loss when stripe rust is severe.

“Some wheat varieties – including Baxter, Bowerbird, Cunningham, Diamondbird, Hybrid Mercury, Janz, Lang, Leichhardt and Whistler – are expected to show noticeably greater levels of disease when challenged by the WA rust strain.

“The variety H45 appeared to be more affected by the WA strain, even though it is already  moderately susceptible to strain 110 E143A+, which has been in eastern Australia for many years.”

Dr Wellings advised growers expecting lower ranked varieties to be in high yielding situations in 2004 to  monitor those crops carefully, because early decisions on fungicide spraying would be important.

Paddock hygiene would also be essential; over summer growth of wheats ranking six or  less would assist rust survival.

“The Cobbitty team is also looking at rust in other winter cereals – barley, oats and triticale –  and there are indications barley grass stripe rust has moved into crop barley,” Dr Wellings said.

“We’re collecting isolates of barley grass stripe rust in South Australia, Victoria and southern NSW  and trying to work out whether its spread into crops is a result of the cool spring or a change in the rust itself.”

The Australian Cereal Rust Control Program is supported by the nation’s graingrowers and the Federal Government through the Grains Research and Development Corporation.