A deadly new airborne wheat rust disease threatens wheat production and food security throughout Afghanistan. The disease also threatens the region that stretches east across neighboring Pakistan and into India.

Named "Ug99", this deadly new form of wheat stem rust has thus far been found in Kenya, Uganda, Ethiopia and Sudan, and has more recently spread into Asia, to Yemen and now Iran. "It is only a matter of time before it reaches Afghanistan and then South Asia," said Dr. Mahmoud Solh, Director General of the International Center for Agricultural Research in the Dry Areas (ICARDA) in Aleppo, Syria. "We have been lucky so far, but we know that the disease is heading in this direction, and most of the varieties planted in the region are at risk. In fact, most of the wheat varieties used around the world are vulnerable to this stem rust; the last major outbreak of stem rust was seen during the 1950s."

wheat stem rust

The effects of ug99 wheat stem rust shown here. (photo credit:environmentdebate.wordpress.com)

"The stem rust threat is particularly dangerous because nearly all farmers in Afghanistan grow wheat for food or sale," said Dr. Mahmood Osmanzai, a wheat scientist from the International Center for the Improvement of Maize and Wheat (CIMMYT), who is based in the country. "A wheat stem rust epidemic would be economically and culturally significant and far reaching."

ICARDA scientist Dr. Javed Rizvi notes that farmers often lack credit to purchase the new seed. This means that the associations that produce the seed feel pressured to sell their stocks for food rather than waiting for farmers to pay the market price. "There are still too few places to store seed until the planting season in November," Rizvi said. "At this pace, it will be at least four years before enough seed of new wheat varieties becomes available, which is far too long, given the imminent danger of Ug99."

The country's agricultural research and extension capacity and infrastructure have been severely damaged after decades of war. ICARDA and CIMMYT are making efforts to help Afghan farmers get back on their feet by helping them improve and sustain crop production. These include the testing, evaluation, release and seed multiplication not only of wheat but of improved maize, chickpeas, mung beans, rice and potato varieties in collaboration with the International Rice Research Institute (IRRI) based in the Philippines, International Center for Research in the Semi-Arid Tropics (ICRISAT) in India, the International Potato Center (CIP) in Peru, and the World Vegetable Center in Taiwan; promoting the use of high-value crops, like mint and saffron; and of conservation agriculture practices; as well as various efforts to train Afghan researchers/extension workers and farmers.

Osmanzai noted that six new promising wheat and three maize varieties have been released in Afghanistan in the last seven years, following an intensive process of testing, release and certification to ensure that they are suitable for local conditions. He says the emerging stem rust threat has added a new urgency to ongoing efforts to improve agriculture in the region.

"CIMMYT and ICARDA have been providing improved seed as well as training Afghan wheat scientists since the 1970s," Rizvi said. "To tackle Ug99, we would need to move faster than we ever have before, in order to address the threat and replace old varieties with new resistant ones."

Ensuring food security in Afghanistan and neighboring countries is becoming increasingly difficult, according to the scientists responsible for improving agriculture in Afghanistan. A drought during the 2008 growing season severely reduced wheat harvests and caused grain shortages. And Afghanistan continues to face a potential "food deficit," although spring rains this year made possible a bumper harvest of 3.4 million tons of wheat, a jump of 127 percent over last year, according to the US Department of Agriculture.

"This year's harvest was good, but some of it was damaged by a second wheat disease known as yellow rust. This shriveled the grain, so there could be unexpected deficits," Osmanzai said. "Afghanistan was self-sufficient in wheat in 1978, due in part to widespread adoption of varieties from CIMMYT. But production more recently has ranged from 2.3 to 4.5 million tons-far short of the yearly 5 million tons consumed."

According to Rizvi and Osmanzai, addressing wheat diseases such as stem rust and yellow rust is vital to any strategy to improve food security and agriculture in Afghanistan and of crucial importance in preventing the spread of Ug99 into Pakistan and India. Stem rust has plagued wheat farmers worldwide for thousands of years, but for the last 50 years it has been largely forgotten thanks to resistant varieties developed by a group of scientists led by Norman Borlaug, who earned a Nobel Peace Prize for his efforts.

Unfortunately, in 1998, the Ug99 stem rust variant discovered in Uganda showed itself able to overcome the resistance that was first established by Borlaug's team. Experts watched with alarm as Ug99 quickly moved to Kenya, where it proved capable of cutting wheat yields by 20 to 80 percent, with isolated incidents of total crop destruction.

Earlier this year, at the Borlaug Global Rust Initiative 2009 Technical Workshop in Mexico, researchers from CIMMYT, ICARDA, the Kenya Agricultural Research Institute (KARI), and the Ethiopian Institute for Agricultural Research (EIAR) described a technological breakthrough-the development of new varieties of wheat that are not only resistant to Ug99, but also produce more grain than today's most popular varieties. The scientists said their research suggests that 90 percent of wheat varieties planted around the world are vulnerable to Ug99, and that the pathogen is now in Kenya, Uganda, Ethiopia, Sudan, Yemen and Iran, and is on the march toward South Asia.

A global mapping system, modified from FAO models that track movement of locusts, is being put in place to follow and predict the pathway of Ug99, but Rizvi and his colleagues have launched their own simple early warning system using biological rust trap nurseries at three locations, including Herat near the Iranian border and Nangarhar near the Pakistani borders.

"So far the plants have been clean," Rizvi says, "but there's no telling how long before the new stem rust appears here."