CANBERRA CITY, AUSTRALIA — A nationwide outbreak of wheat rust strain Ug99 could cost Australia up to $1.4 billion over the next 10 years, according to a new report from the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES).
Wheat stem rust is a fungal disease that can affect wheat, barley, oat, rye and triticale when seasonal conditions are favorable. The fungus survives on host plants and can spread quickly over large distances by wind, movements of infected plant materials and contaminated farm machinery, equipment and clothing.
“The Ug99 strain is not present in Australia but poses a major risk to the wheat industry in terms of revenue losses and increased production costs, should it arrive in the country,” said Steve Hatfield-Dodds, PhD, executive director of ABARES. “It is a highly virulent strain of wheat stem rust that has overcome 17 of 34 stem rust resistance genes found in wheat.”
The Ug99 strain got its name from a variety that was found in Uganda in 1999.
In general, wheat stem rust can attack all above-ground parts of the plant, including the stem, leaves and inflorescence. Infected wheat plants also may produce shriveled grain. According to ABARES, an untreated infection may reduce grain yield by up to 90%.
In its report, ABARES noted a wide variance in potential costs from a possible infestation of Ug99.
“It estimates the economic impact over 10 years, of three disease spread scenarios ranging from $574 million for a spread to wheat-growing areas in the western region, to $1.4 billion for a spread which covers all wheat growing areas in Australia,” Hatfield-Dodds said. “Disruptions to Australian wheat exports may also result if Ug99 -sensitive markets were to ban imports of Australian wheat.
“Eradication of Ug99 would likely only be technically feasible if the rust is detected while still contained within a very small area with a light spore load, so it is crucial we take measures to keep Ug99 from entering the country in the first place.”
Hatfield-Dodds said Australia is undertaking preparedness activities to manage the risk posed by Ug99, with significant work being done in surveillance. He said the country is monitoring pathogen populations over time to track potential virulence evolution, and pre-breeding for germplasm resistance.
Wheat stem rust is present in many wheat growing areas throughout the world, and around two-thirds of global wheat growing areas are climatically suitable for the disease. The most recent severe outbreak of wheat rust in Australia took place in 1973, which ABARES said cost the country’s wheat industry between $200 million and $300 million.