New stripe rust strain hits triticale crops (National, 7, November 2007)

Grain producers have been urged to give stripe rust a greater priority when selecting triticale varieties following the discovery of a new strain of the airborne fungus.

The University of Sydney’s Colin Wellings said testing completed by the Australian Cereal Rust Control Program, supported by growers and the Australian Government through the Grains Research and Development Corporation (GRDC), had shown the new stripe rust pathotype was a threat to several popular varieties.

“The varieties Jackie, Breakwell, Speedee, Abacus, Prime 322, Kosciuszko, Hillary and Madonna are all vulnerable to the new pathotype,” Dr Wellings said. “It appears to overcome resistance provided by the Yr9 gene, as well as another presumed single resistance gene that is yet to be identified.

“The good news is that several other triticale varieties such as Ticket and Tahara appear to be resistant to the new pathotype.”

Dr Wellings said he feared the new strain could be widespread, particularly in southern NSW. The strain was first found on a sample of Jackie triticale at Bingara, near Moree in northern NSW.

“It was the first rust sample I received for the season and it took a while for us to determine it was a new strain,” he said. “We’re now going back and checking other samples received during the season to determine how widespread the new pathotype might be.”

Dr Wellings said that like the ‘Yr17’ pathotype affecting wheat crops, the new triticale stripe rust strain appears to have emerged from the current dominant ‘Western Australian’ stripe rust pathotype. He said the new variant of this pathotype had implications for wheat producers.

“The new pathotype may increase the stripe rust pressure on wheat because it is an additional direct threat to highly susceptible wheat varieties,” he said. “It potentially broadens the population base from which new pathotypes can emerge, and it increases the potential for stripe rust build-up on out-of-season triticale volunteers or early-sown triticale crops.

“Triticale growers will need to pay more attention to managing stripe rust, particularly in early-sown crops. Several of the susceptible varieties are dual-purpose, sown early for grazing, which maximises the chance of disease carryover from one season to the next, and for early-season disease build-up.

“Grazing can control the canopy and may assist to limit early disease build-up, but if those paddocks are then closed up for grain production then growers may need to consider a budget for a stripe rust spray, particularly in areas with high yield potential.”

Growers seeking information about rust management are encouraged to visit the GRDC rust links website page at www.grdc.com.au/rustlinks.
GRDC Code: US315

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