Yemen’s government has launched a campaign to combat a virulent and potentially devastating wheat disease after the United Nations Food and Agriculture Organization (FAO) recently warned of its spread to the Arabian Peninsular from east Africa.

"Yemen, in particular, should be on the alert, step up field monitoring and training and prepare for direct control interventions in disease hot spots,” FAO said in a statement on 12 April. “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."

The disease is known as wheat stem rust, wheat black rust or puccinia graminis. FAO confirmed in a recent field mission to Yemen that a particularly virulent strain of the disease, called Ug99, had affected wheat fields in the country for the first time.

Ug99 gets its name from its place and date of discovery – Uganda in 1999. It subsequently spread to Kenya and Ethiopia, according to FAO.

“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 US and Canada for further analysis. There is a high risk that the disease could also spread to Sudan," FAO said.

The spores of wheat rust are mostly carried by wind over long distances, according to FAO specialists. Wheat stem rust is capable of causing severe agricultural losses by destroying entire wheat fields. The disease attacks wheat stems and shows rust-colored orange patches on infected plants.

It is estimated that as much as 80 per cent of all wheat varieties planted in Asia and Africa are susceptible to the Ug99 strain.

Government fights back

In response to this potential threat, the Yemeni Ministry of Agriculture and Irrigation has begun a programme to combat wheat stem rust.

Dr Mansour al-Aqil, general director of the General Department for Agricultural Information at the ministry, told IRIN on Sunday that the programme aims to plant detection samples among crops, which help discover the existence of the disease.

Al-Aqil said two experts from the International Center for Agricultural Research in the Dry Areas (ICARDA) and FAO come to Yemen in February and visited nurseries where they saw samples revealing wheat stem rust in different provinces.

According to al-Aqil, there are three kinds of wheat rust disease in Yemen: yellow rust, orange rust, and black rust. Yellow and orange rust mostly attack leaves, while black rust attacks the stem, he said. The disease affects the southern parts of Yemen more than the northern areas, which are colder, he said.

Wheat is the third most grown cereal in Yemen. It is planted in more than 86,000 hectares in most provinces of the country. In 2005, Yemen produced 115,000 tonnes of wheat. A wheat rust epidemic in Yemen would be devastating to the food security of the impoverished nation and to other major wheat-producing countries should it spread.

“Global wheat yields could be at risk if the stem rust spreads to major wheat-producing countries," Dr Jacques Diouf, FAO director-general, said in a recent statement.

In the late 1980s, a virulent strain of yellow rust emerged in east Africa and crossed the Red Sea to Yemen, according to FAO. It then moved into the Near East and Central Asia, reaching the wheat fields of southern Asia within four years. Major yellow rust epidemics were subsequently recorded in Egypt, Syria, Turkey, Iran, Iraq, Afghanistan and Pakistan, with wheat losses of more than US $1 billion in value.

"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," Diouf said.