Grains Research and Development

Date: 18.01.2016

Rust resistance checks recommended

Author: Melissa Williams

Wheat leaf rust can significantly reduce wheat yields on susceptible varieties, so it is best to check updated resistance ratings prior to sowing.

PHOTO: ACRCP

Western Australian growers are encouraged to choose wheat varieties carefully for the 2016 season on the back of an eastern Australian wheat leaf rust (Puccinia triticina) pathotype being identified in WA in 2015.

The new pathotype may cause the rust-resistance ratings of several wheat varieties to change, pending further analysis by researchers.

It is understood that Mace may become more susceptible to leaf rust. Other varieties to monitor closely include Arrino, Binnu, Emu Rock, LongReach Envoy, Estoc, Grenade CL Plus, Tammarin Rock and Zippy.

The wheat leaf rust pathotype new to WA was submitted to the GRDC-supported Australian Cereal Rust Control Program (ACRCP) at the University of Sydney, where it was identified by Professor Robert Park.

He says the pathotype, called 104-1,3,4,6,7,8,10,12 +Lr37, was identified in samples of leaf-rusted wheat collected during 2015 from four separate locations in WA’s northern agricultural region – near Carnamah, Yuna, Coorow and Woorree (close to the town of Geraldton).

“This pathotype was first detected in South Australia in August 2014 and has since spread throughout much of the eastern Australian grainbelt – and now to WA,” Professor Park says.

“It is only the third example of a wheat rust isolate migrating from eastern Australia to WA in the past 25 years, all three being wheat leaf rust.”

Department of Agriculture and Food, WA (DAFWA), plant pathologist Geoff Thomas says the incursion of the pathotype is concerning, particularly following the 2013 identification of the separate 76-1,3,5,7,9,10,12 +Lr37 pathotype. This resulted in the resistance ratings of varieties, including Mace, being reclassified.

“Changes in variety classifications highlight the impact of rust incursions and demonstrate the importance of continued vigilance to stop the introduction of pathotypes and monitoring for early identification of incursions,” Mr Thomas says.

“To minimise the risk of crop damage from rust this season, WA growers need to think carefully about the varieties they have retained or plan to source for crop seed for 2016.”

The DAFWA wheat variety guide and regularly updated variety disease ratings are available online from the DAFWA website  or from the Rust Bust website.

Mr Thomas says controlling the ‘green bridge’ and monitoring summer/autumn regrowth are also imperative to limit carry-over of rust into this growing season.

More information:

Professor Robert Park, ACRCP, University of Sydney,
02 9351 8806,
robert.park@sydney.edu.au

Information about developing a rust management strategy can be found on the Rust Bust website, including a ‘Rust Bust Management Checklist’.

The ACRCP is one of the GRDC’s core investments to monitor, assess and develop a rust management strategy for Australian growers.

GRDC Cereal Fungicides fact sheet
DAFWA wheat variety guide and variety disease ratings

End of Ground Cover issue 120 (Western region edition)
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Ground Cover Supplement – 'Tactical cereal agronomy'

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