About 90% of the world’s wheat has little or no protection against Ug99, a stem-rust disease.
Fungal disease Ug99 threatens cereals worldwide
In less than a decade, nearly 200 scientists in 50 countries have mobilized to address the threat of Ug99, a stem rust disease that threatens cereals crops worldwide.
Scientists at the University of Minnesota and USDA–Agricultural Research Service’s Cereal Disease Laboratory (CDL) in St. Paul lead much of the research on this fungal disease.
About 90% of the world’s wheat has little or no protection against Ug99. To date, it has not reached the U.S., though most researchers expect it will.
"It’s not a matter of if but when we will see Ug99 here," says wheat expert and Farm Journal columnist Phil Needham, who consults with wheat producers in the U.S. and Canada.
The National Association of Wheat Growers reports that more than 40 mil-lion acres of U.S. wheat are in jeopardy.
The good news, Needham says, is that fungicides are available in the U.S. to control Ug99, which is not neces-sarily true in other parts of the world.
Disease changes course. To date, Ug99 spores have decimated cereal crops, particularly wheat, in Kenya and Ethiopia. They have also been found in Sudan, Yemen and Iran.
"There are three variants known in South Africa and at least one in Zimbabwe," says Les Szabo, CDL research geneticist and acting research leader. The CDL is one of only two research facilities in the world that can identify races of foreign rusts.
"There’s good evidence that Ug99 pathogens have been airborne and moved into Australia," he adds. "That opens up broader pathways for natural movement to occur."
The disease includes seven variants, Szabo notes, making the breeding process to develop new resistant wheat varieties more of a challenge.
"It seems like every year we are discovering a new variant," he says. "There’s a lot more variation than we originally thought."
The disease is quick to adapt and overcome adversity. Szabo says that Ug99 quickly overcame single-gene resistance. As a result, scientists will need to develop wheat varieties that contain multiple resistance genes stacked in the same plant in order to effectively repel the disease.
- March 2012