New Form of Rust Threatens World Wheat

East African Stem Rust is capable of spreading to more than half the world’s commercial wheats. Compiled by staff

Published on: Apr 20, 2006

About 70% of U.S. wheat varieties - and perhaps more of varieties used in other countries - are susceptible to an East African Stem Rust first discovered in 1999.

The new form of rust, which first appeared in Uganda in 1999 and Kenya and Ethiopia in 2000, is, so far, contained outside of East Africa. But, between 70 and 75% of wheat in India and Pakistan are also susceptible to this rust; wheat in Egypt and China are thought to have similar vulnerabilities.

Kay Simmons, the national program leader for plants genetics and grain crops at USDA's Agricultural Research Service, spoke at a meeting recently about the USDA response to this potential threat.

She says the department was first alerted to the rust issue about two years ago. Since then the rust has been very carefully brought to labs in Minnesota for testing, where the vulnerability of U.S. wheat varieties was determined.

Simmons says USDA was "surprised" and "alarmed" at the potential susceptibility and quickly sent samples from the National Small Grains Repository to Kenya to be planted and tested for vulnerability and/or potential resistance. Researchers are now getting ready to send another round of seeds to Kenya for more testing.

John Dodds, deputy director general of the International Maize and Wheat Improvement Center, says Ug99, as the new rust is known, is capable of spreading to more than half the world’s commercial wheats, and that it is almost inevitable that it will spread, either naturally by wind or accidentally, likely through a traveler’s clothing.

Some control strategies researchers are working on include tracking, genetic resistance research, breeding for resistance and creating plans for emergency control through chemicals. Some promising emergency replacement varieties have already been identified.

The lecture was headlined by Nobel Laureate Norman Borlaug, who won a Peace Prize for his work with the Green Revolution. He spoke on the history of international wheat research and what was done in reaction to a major rust epidemic in the 1950s.

For more information about the stem rust issue, visit: www.globalrust.org.