Experts have warned there is a high risk that Australian grain growers, particularly in eastern Australia, will experience stripe rust pressure during the winter growing season, with wet summer conditions and carryover from last year creating the perfect storm for the disease.
The risk of stripe rust in Western Australia is generally lower than eastern states, but there was infection found in wheat crops in late 2021, so growers should not be complacent.
Updated disease ratings for wheat varieties have been published on the GRDC's National Variety Trials’ (NVT) website - which could help growers avoid highly susceptible varieties in light of the risk, or to develop appropriate management plans to minimise impacts.
Director of the Australian Cereal Rust Control Program, based at the University of Sydney’s Plant Breeding Institute, Professor Robert Park says irrespective of whether growers have already chosen their varieties for the coming season or they’re still yet to decide, they should be reviewing the updated disease ratings to determine a variety’s risk, as they could have changed from previous years.
“The disease rating is influenced by the pathotypes that were present in the 2021 season - pathotypes are the main driver of a variety’s response to rust,” he says.
“A wheat variety can be completely resistant to one pathotype and yet susceptible to another. It’s particularly important at this time of year that growers are reviewing the disease ratings for their regions and putting management strategies in place if needed.”
Senior Plant Pathologist at Agriculture Victoria, and leader of many GRDC disease management projects, Dr Grant Hollaway, says growers who plan to sow susceptible varieties will need to consider early fungicide intervention this season to control stripe rust pressure.
“Usually, growers can be hesitant to invest in fungicide right at the start of the season, as it can be a waste of money if disease pressure doesn’t eventuate,” he says.
“This season, given the high risks, growers with susceptible varieties are more than likely to get a return on upfront applications, such as flutriafol on fertiliser.
“Reviewing the updated ratings gives growers an opportunity to understand their fungicide needs and gives them time to secure product ahead of the season.”
Professor Park further supported the need for growers to be prepared for upfront fungicide management when growing susceptible varieties, as he said the risk of stripe rust causing yield loss was extremely high without proper management.
“The threat we’re facing this year has been exacerbated by the green bridge that’s been generated by the wet summer conditions - the opportunity for rust to survive on self-sown volunteer wheat that’s established due to all the rain is much higher,” he says.
“We’re anticipating if things stay wet, which forecasts have predicted, that upfront treatments will be crucial in delaying the stripe rust epidemic”.
“If a variety is completely susceptible, and there’s early stripe rust infection, growers could face yield losses up to 50 per cent in the absence of any control measures”
GRDC’s Northern Crop Protection Manager Vicki Green says the NVT’s disease ratings, supported by GRDC investment, are an important tool for growers as they provide annually reviewed ratings based on in-field assessments of disease across multiple trials across the country.
“GRDC prioritises investing in disease management and communicating risks with growers, to help them understand how their management decisions could impact their bottom line,” she says.
“When considering this year’s anticipated stripe rust risk, we want to encourage growers to use our nationally standardised system to understand how their chosen varieties could perform in their region and to make more informed management decisions.”
You can view the updated disease ratings via GRDC’s NVT website.
More information: managing stripe rust.