Stripe rust pathotype discovery underlines need for vigilance
Author: Sharon Watt | Date: 01 Jun 2018
Grain growers in the southern cropping region are encouraged to closely monitor their wheat crops for stripe rust this season, following the detection of a new pathotype of the wheat stripe rust pathogen.
It is the first time since 2010 that a new pathotype of the wheat stripe rust pathogen, Puccinia striiformis f. sp. tritici, has been detected in Australia.
Australian Cereal Rust Control Program researchers at the University of Sydney’s Plant Breeding Institute confirmed the new pathotype in samples received from Horsham (Wimmera) and Normanville (Mallee) in Victoria in late 2017 through the Australian Cereal Rust Survey, a Grains Research and Development Corporation (GRDC) investment.
They say the new pathotype is the first record of virulence for the Yr33 resistance genein Australia and that its impact on wheat varieties will be better understood after the 2018 cropping season.
Dr Grant Hollaway, a Horsham-based senior plant pathologist with Agriculture Victoria, is encouraging growers and advisers to provide samples of stripe rust found in this year’s crops to the Plant Breeding Institute for analysis.
“Stripe rust found on any variety of wheat should be submitted for pathotype analysis,” Dr Hollaway says.
“Having samples analysed will not only inform individual growers about the stripe rust pathotypes in their crops, which in turn assists with proactive disease management, but analysis enables the broader industry to be on the front foot with potential rust outbreaks and the detection of new pathotype mutations and incursions as soon as they occur.”
Infected plant samples can be mailed in paper envelopes (do not use plastic wrapping or plastic-lined packages) and if possible, include the latitude and longitude of the sample location. Direct samples to:
University of Sydney, Australian Cereal Rust Survey, Reply Paid 88076, Narellan NSW 2567.
Dr Hollaway says early greenhouse data from the Plant Breeding Institute and data from the GRDC’s National Variety Trials (NVT) at Horsham last year indicate that the varieties Coolah, LRPB Flanker, Axe, B53, Buchanan, Cobalt, EGA Gregory, Forrest, Gauntlet, Grenade CL Plus, Mitch, Steel, Trojan, Viking and Zen should be monitored closely for stripe rust.
Of the three wheat rust diseases – stripe, stem and leaf – stripe rust is most suited to cooler temperatures that occur during late autumn and early spring. It is therefore usually the first rust disease to appear in a cropping cycle.
Stripe rust reproduces and spreads by spores, which are wind-blown and can travel hundreds of kilometres. The severity of stripe rust within a crop depends on varietal susceptibility, the nitrogen status of the crop, moisture and temperature.
Where very susceptible varieties of wheat are infected with stripe rust, resulting losses can be as high as 80 percent.
Experts say the most powerful tool available to growers to minimise the impact of the disease is resistant varieties. Fungicides for controlling stripe rust should be regarded as a support and not a substitute for growing resistant varieties.
Where fungicides are used as part of a management strategy, growers are encouraged to employ effective fungicide resistance management practices. Knowing previous and anticipated fungicide modes of actions (MoA) used throughout the growing season is essential in resistance management.
Growers should monitor crops to detect infection at the earliest stage possible.
For more information on prevention and management of stripe rust, visit the GRDC-supported Rust Bust resource hub.
Practical information for growers and advisers can be found in the GRDC’s Stripe Rust In Wheat Tips and Tactics publication.
Meanwhile, the GRDC continues to invest in an extensive portfolio of cereal rust-related research, development and extension activities, including the Australian Cereal Rust Control Program which is focused on monitoring the effectiveness of rust-resistance genes in commercial cultivars; determining the implications of new endemic and exotic rust pathotypes for current cultivars; facilitating the discovery of new resistance genes; and allowing pre-emptive resistance breeding.
Grant Hollaway, Agriculture Victoria
03 5362 2111
Sharon Watt, Porter Novelli
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