The challenge
Wheat and barley rusts are prevalent in Australia. They are highly infective diseases that can spread widely and quickly within and between regions and have the potential to cause significant crop damage. Inoculum build up in volunteer cereals and other rust susceptible grasses during the non-cropping phase and/or wet spring weather can result in explosive, devastating rust outbreaks. Globally, it is estimated that over five million tonnes of wheat are lost each year to stripe rust alone.
Fortunately, in Australia, rust epidemics have largely been kept in check over the past 40 years through the selection and cultivation of varieties with adequate rust resistance. However, rust pathogens are highly adaptable and mutate into new strains continuously, requiring constant RD&E efforts to maintain our current levels of control.
The response
Over many years, GRDC has invested in collaborative national and international projects which have helped to deliver superior rust resistant wheat and barley varieties to Australian grain growers.
The work has focused on monitoring Australian cereal rust pathogens, researching new sources of genetic rust resistance that can be used by breeders in the development of rust resistant cultivars, and improving knowledge on the management of cereal varieties.
Research by the University of Sydney and CSIRO through the Australian Cereal Rust Control Program (ACRCP) has helped simplify the breeding of rust resistant wheat and barley by identifying markers for more than 25 resistance genes. These markers have allowed breeders to identify and advance superior lines earlier in their breeding programs.
Together these investments have given growers access to rust resistant varieties with the potential to yield well under local conditions and have also helped preserve the efficacy of fungicide chemistries by reducing the reliance on applications and raising industry adoption of supporting management strategies.
The impact
The research has supported Australian growers to realise seasonal yield potential without setbacks due to rust outbreaks, saving growers an estimated $2.90 per hectare per year due to lost production.
Kym Shepherd grows wheat, barley, field peas and vetch on his property on South Australia's Eyre Peninsula. Since 1981, when he began farming on the property, he has seen minimal rust on a year-on-year basis.
Mr Shepherd selects wheat varieties according to their yield potential, regional agronomic suitability, and their disease resistance ratings.
For in-crop management, he applies a preventative spray relatively early in the season and a second spray around the time of head emergence if seasonal conditions require it. He avoids using the same fungicides two seasons in a row to minimise the risk of resistance and always evaluates previous fungicide applications with his agronomist to inform his disease management planning.
As rusts survive on living plants, Mr Shepherd always sprays out volunteer cereals between growing seasons by applying a knockdown herbicide at the first sign of emergence. He believes his grain quality has not been impacted by rust and believes a preventative approach delivers the best outcomes for his operation.
GRDC is continuing to invest in these important programs to ensure that Australian growers have the right tools and knowledge to proactively manage rusts, and cost benefit analysis figures generated by the GRDC suggest investments across the suite of cereal rust research projects will return $5.70 for every $1 spent over the next 25 years.