Sounding an Alarm

Wheat in peril from stem rust outbreak, expert panel warns.

Pathologists Ravi Singh and Ruth Wanyera examine wheat infected with stem rust in Kenya.

An expert panel commissioned by the Rockefeller Foundation to study the potential for a global stem rust epidemic in wheat has called for a massive, ten-point program of action to prevent a potential food security crisis.

The group focused its work in eastern Africa where the new strain of stem rust called Ug99 was first identified. The fungus, whose spores are carried by the wind, is spreading in the region, damaging wheat crops in Uganda, Kenya, and Ethiopia.

The greatest danger is that the new stem rust strain will spread to intensive wheat growing areas of Asia. The report warns, “It is only a matter of time until Ug99 reaches across the Saudi Arabian peninsula and into the Middle East, South Asia, and eventually, East Asia and the Americas. However, the current crisis is a wake-up call about the continuing, and potentially devastating, impact that the rust pathogens can have on susceptible cereals, and especially a staple food like wheat.”

But the report also says it is not too late to act to prevent potential disaster, “Plant breeders and pathologists still have time to screen for resistant genotypes, and to get these multiplied and into farmers’ fields,” say the panel members.

Wheat is a vital world crop, grown, consumed, and traded around the world. Any significant disruption in wheat production will have impacts on global food security. A 10% reduction in global yield is equivalent to sixty million tons of crop loss worth US$ 9 billion.

As far back as the Roman Empire, stem rust epidemics have decimated wheat fields over large swaths of continents. In more modern times, stem rust has largely been controlled through the deployment of wheat varieties specifically bred to resist the disease. It is the breakdown of this resistance by this new string of the pathogen that particularly alarms scientists and policymakers.

As an example of how the disease can travel, here a virulent stripe rust starts in the highlands of East African and makes its way to South Asia.

An initial analysis of global wind patterns and environmental factors conduced by CIMMYT’s Geographic Information Systems unit confirms there is a high potential for the fungal spores to spread from eastern Africa into the Arabian peninsula, Iran, and the expansive wheat growing regions of Pakistan, India, and Bangladesh. The expert panel report confirmed that many of the wheat varieties grown in these regions are susceptible to the new strain of the fungus.

CIMMYT has been screening materials in its gene bank for sources of resistance to the new rust strain and has made some progress in identifying promising candidates. Nevertheless, as the expert panel points out, there is a huge job to be done in breeding, monitoring the progress of the disease, and eventually disseminating any new resistant varieties. CIMMYT and ICARDA, with national partners from Kenya and Ethiopia, have convened a meeting of stakeholders and donors from around the world to work on a plan of action this month.

For further information, contact Ravi Singh (r.singh@cgiar.org).

Click on the title to see the complete report by the Expert Panel on the Stem Rust Outbreak in Eastern Africa: Sounding an Alarm on Global Stem Rust (pdf 200 KB)