A new and virulent fungus that attacks a wide range of wheat varieties
has spread from East Africa to Yemen on the Arabian Peninsula, FAO
photo courtesy of FAO
The wheat stem rust (Puccinia graminis), also known as wheat black
rust, is capable of causing severe losses and can destroy entire
It is estimated that as much as 80 percent of all wheat varieties
planted in Asia and Africa are susceptible to this new strain. The
spores of wheat rust are mostly carried by wind over long distances
and across continents.
“Global wheat yields could be at risk if the stem rust spreads
to major wheat producing countries,” said FAO Director-General
Dr Jacques Diouf.
“The fungus can spread rapidly and has the potential to cause
global crop epidemics and wheat harvest losses of several billion
dollars. This could lead to increased wheat prices and local or regional
food shortages. Developing countries that are relying on wheat and
do not have access to resistant varieties will be particularly hit,” Dr
FAO has joined the International Center for Agricultural Research
in the Dry Areas (ICARDA) and the International Maize and Wheat Improvement
Center (CIMMYT), which are leading the Global Rust Initiative (GRI),
an international consortium to fight the spread of rust fungus diseases
around the world. Canada, the United States and India are the main
donors to the GRI.
The new pathogen first emerged in Uganda in 1999 and is therefore
called Ug99. It subsequently spread to Kenya and Ethiopia.
A recent FAO mission in the field has confirmed for the first time
that Ug99 has affected wheat fields in Yemen. It appears that the
Ug99 strain found in Yemen is already more virulent than the one
found in East Africa. Samples of the pathogen were sent to the United
States and Canada for further analysis. There is a high risk that
the disease could also spread to Sudan.
Wind-borne transboundary pests and diseases can cause serious damage
to crop production.
In the late 1980s, a virulent strain of yellow rust, a wheat disease
similar to stem rust, emerged in East Africa and crossed the Red
Sea into Yemen. It then moved into the Near East and Central Asia,
reaching wheat fields of South Asia within four years. Major yellow
rust epidemics were recorded with wheat losses of more than one billion
Based on monitoring of Desert Locust pathways, FAO does not exclude
that wind currents could carry Ug99 stem rust spores from Yemen northwards
along the Red Sea to Egypt or through the Saudi Arabian Peninsula
towards countries in the Near East.
FAO urges affected countries and countries at risk to increase their
Yemen in particular should be on the alert, step up field monitoring
and training and prepare for direct control interventions in disease
hot spots. Most important, control measures in affected countries
should include the introduction of more resistant wheat varieties
and restricting planting dates to break the disease cycle.
FAO, ICARDA and CIMMYT will support countries in developing resistant
varieties, producing their clean quality seeds, upgrading national
plant protection and plant breeding services and developing contingency
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