A virulent strain of stripe rust threatens crops across Africa and Asia

USDA/Yue Jin

An epidemic caused by a new strain of wheat fungus could cause billions of dollars in crop losses across North Africa, the Middle East and Central Asia, according to researchers.

The wheat stripe rust — or yellow rust (Yr) — epidemic is far worse than predicted, scientists from various Middle-Eastern institutions have found.

"The situation is severe, some farmers will suffer 30–60 per cent yield loss. In the worst cases, yield loss is 100 per cent," said Maarten Van Ginkel, deputy-director general for research at the International Center for Agricultural Research in the Dry Areas (ICARDA), Syria.

Key cereal production regions are affected and in some countries, like Syria, up to 80 per cent of fields are affected, according to recent surveys. Wheat agriculture provides food and livelihoods for hundreds of millions of people in these regions, which already suffer from production constraints caused by drought.

"Urgent action is needed to protect wheat crops on some 50 million hectares, and research centres and industry are urged to work together to fight the disease," Mahmoud Solh, director general of ICARDA, told SciDev.Net.

The comments come as experts gather for a meeting next week (30–31 May) in St Petersburg, Russia to map out new strategies for combating wheat rust pathogens that are threatening the world's wheat supplies.

The areas most affected by the stripe rust include Iran, Iraq, Morocco and Syria, according to scientists at ICARDA. Wheat fields in Afghanistan, Algeria and Tunisia are also affected.

Yellow rust attacks all plant parts, causing most damage to the leaves. It occurs early in the season and can continue to affect the crop until maturity, if night temperatures remain sufficiently low. Because of this long cycle, damage can be severe, said Van Ginkel.

The pathogen race able to overcome a major wheat resistance gene first emerged in 2002 in South Asia but unfavourable weather conditions limited its spread until 2009, when it started re-appearing.

Van Ginkel said his team is documenting and analysing the impact of the recent outbreaks.

Newly developed, resistant varieties of wheat are already available. But national research programmes must accelerate the process of releasing these varieties for cultivation and producing and distributing enough seeds from these varieties.

Governments will have to take appropriate measures, such as planting high-yielding, resistant varieties and continually monitoring affected areas, to prevent new outbreaks next year, Solh told SciDev.Net.  

Yellow rust is different from the reddish brown fungus, Ug99, which is a type of stem rust that emerged in East Africa ten years ago.

"While the Ug99 race of stem rust has received considerable global attention in recent years, ICARDA has always stressed to need to remain vigilant against stripe rust," Solh said (see The race is on to stop the red menace fungus: Ug99).