Grow resistant varieties
From the December 2008 edition of Agriculture Today.
New stripe rust pathotype
Dr Colin Wellings, on secondment to the University of Sydney’s Plant Breeding Institute (PBI) at Cobbitty, said greenhouse experiments revealed a new stripe rust pathotype had features identical to the Jackie pathotype, but that a differential test wheat variety carrying the Yr27 gene had shown a susceptible reaction.
Current varieties carrying Yr27 include GBA Combat, GBA Ruby, Merinda and Mira, and these must be considered at risk until further information becomes available.
Dr Wellings said the newly named Jackie Yr27 pathotype was avirulent for the Yr17 resistance gene, so this gene should provide protection against the new strain.
However, a stripe rust pathotype virulent for Yr17 was also widespread in eastern Australia, so Yr17 varieties were at risk to this pathotype.
Growers’ best defence against a newly discovered stripe rust pathotype is to grow resistant varieties, say the NSW Department of Primary Industries (DPI) and the Grains Research and Development Corporation (GRDC).
A sample of stripe rust collected from a wheat crop in north-east Victoria is the first Australian pathotype with virulence for the Yr27 resistance gene.
“Growers are advised to take note of variety response to stripe rust, and other diseases likely to limit yield, in selecting varieties for 2009,” DPI’s Dr Colin Wellings said.
“The potential for similar stripe rust problems in 2009 will depend on pathogen survival over summer and the timing of first reports of the disease.
“Green bridge control will be important if summer conditions are conducive to stubble regrowth.”
Dr Wellings says management decisions at planting will also be important, especially the need to consider early season fungicide protection.
“Choice of strategy will range from in-furrow applications, fertiliser coatings or seed applications using fungicides of varying expense and growers should seek local advice,” he said.
“When using early season chemical protection, care should be taken in managing grazing cereals, because withholding periods will be important.”
Dr Wellings works in association with the Australian Cereal Rust Control Program (ACRCP), which is supported by growers and the Australian Government through the GRDC.
Contact Dr Colin Wellings, Cobbitty, (02) 9351 8826 or visit www.grdc.com.au/rustlinks
