by Wagdy Sawahel, SciDev.Net

A virulent wheat disease now on the move from Africa to the Arabian Peninsula could devastate world wheat crops and threaten food security, warn scientists.

Known as Ug99, this new form of stem rust has spread from Ethiopia, Kenya and Uganda over the Red Sea to Yemen. Most wheat crops are susceptible to stem rust.

The Global Rust Initiative (GRI) — a partnership of international agricultural research centres — and the Agricultural Research Service of the US Department of Agriculture confirmed infected crops in Yemen, with evidence of further infections in Sudan.

The Mexico-based International Maize and Wheat Improvement Center (CIMMYT) predicts that windborne spores could easily spread to India, Pakistan, the Middle East and North Africa, which together grow about 25 per cent of the world's wheat. The annual losses could total some US$3 billion.

M. E. Tusneem, chairman of Pakistan's Agriculture Research Council, warned that the disease would have a "major impact" on food security if not controlled. Global wheat stocks were, he noted, at a historic low.

In a CIMMYT press release, US wheat scientist and Nobel laureate Norman Borlaug is quoted saying, "We know what to do and how to do it. All we need are the financial resources, scientific cooperation and political will."

Rick Ward, coordinator of GRI, told SciDev.Net that the disease could be controlled if farmers adopt resistant wheat varieties. He said "good progress" had already been made toward identifying such varieties in collaboration with the National Research Programmes in East Africa.

According to Ward, crop improvement specialists create and test thousands of new wheat strains each year.

Suitable strains would initially be available for farmers in quantities of 10–100 kilograms — enough for one hectare at most. This would make speeding up seed production and eliminating policy barriers critical.

Ward stressed the importance of monitoring and early warning systems. He said there was a need to train young scientists about the disease "since stem rust has not threatened world wheat for 40–50 years, leaving us with very little hands-on experience".