Preventive and adaptive action is crucial as climate change is altering the patterns of crop pests. Scientists at CGIAR are working to prepare farmers for the new threats they may face.

Fighting back against deadly wheat rust

Farmers sharing their experiences with new wheat seed varieties (photo: Pete Chinn/ICARDA)
Farmers sharing their experiences with new wheat seed varieties, photo: Pete Chinn/ICARDA

Ethiopian farmer Ato Beriss Felissa opted to grow wheat on his smallholder farm because of the high returns it promised him and his family. But in 2010, a dangerous combination of unusually cool temperatures, above average rainfall and vulnerable seed stock brought disaster. His crop, like that of many other farmers in the country, was decimated by wheat yellow rust. This destructive fungal disease, which severely stunts and weakens wheat crops, infected more than 400,000 hectares, causing losses of up to 80 per cent in some regions.

“When the disease struck, it destroyed my entire harvest. We were starving. It was a terrible time,” recalls the farmer.

As well as hitting household income, the disease also affected food and nutritional security. Wheat prices soared overnight and many families were forced to sell assets and reduce the amount of food they gave to their families. Safia Suale, a mother of seven who farms in the Ethiopian highlands of Oromia, was one of them.

“To cope, we had to sell our livestock,” she said. “But even then we still didn’t have enough food to eat after the crops failed. Often we survived on just one meal a day.”

Globally, the three wheat rusts – stem, leaf and stripe (also known as yellow) rust – are the most economically damaging diseases affecting wheat. All inflict devastating losses when epidemics occur, but stem and stripe rust are the most feared, inflicting losses of 60 per cent or more, causing massive damage to farmers’ incomes and price rises for low-income consumers as wheat supplies are disrupted. In recent years, climate change has exacerbated the problem, making outbreaks more frequent and more severe. Poor smallholder farmers and consumers are especially vulnerable.

Click to watch "Combating the threat of Wheat Stripe (Yellow) Rust", an ICARDA video
Click to watch "Combating the threat of Wheat Stripe (Yellow) Rust", an ICARDA video

A video produced by ICARDA  – a member of the CGIAR Consortium – shows how, with partners from the Ethiopian Institute of Agricultural Research (EIAR) and funding from USAID, CGIAR scientists helped to mount a coordinated fightback against the 2010 rust outbreak in Ethiopia. Drawing on the extensive experience of CGIAR research in tackling wheat rust disease, a team of scientists from ICARDA managed to isolate a rust-resistant wheat variety that could protect crops while giving farmers the high yields they sought. The project involved painstakingly screening more than 5,000 cultivars and landraces so as to breed cultivars with all-round resistance to the disease, which would also be suited to a variety of environmental and climatic conditions.

Farmer-to-farmer seed distribution

To fast-track the process of getting new varieties into fields, seed multiplication and distribution were designed as a central feature of the program and a farmer-to-farmer model of distribution proved a winning formula. Farmer field days accelerated the update further as they allowed farmers reluctant to take the risk of new varieties to hear the experiences of other farmers who have successfully used the new seeds and are enjoying increased yields.

Farmer Field Days. Photo: Pete Chinn/ICARDA
Farmers get to share their experiences with new seed technologies. Field days have proven to be hugely successful as it helped reluctant farmers change their minds and try new seeds

In the first two years of the project, the new rust-resistant wheat varieties reached about 26 per cent of Ethiopia’s total wheat growing area. The seeds have now reached more than 13,000 farmers. Their yields have increased from the national annual average of 2 tonnes/ha to a figure of 3.3 t/ha.

However, as Nobel Prize winner Norman Borlaug once remarked, wheat rust is a “disease that never sleeps”, and there is no room for complacency. Preventive and adaptive action is crucial as climate change is altering the patterns of crop pests, and scientists at CGIAR are working to prepare farmers for the new threats they may face.

Researchers at the CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS) are working on a wider-ranging approach. Strategies being investigated include combining the introduction of more resilient wheat varieties with making climate-smart agriculture practices available to farmers. These may include better climate information services, emergency seed stores and index-based crop insurance.

The Ethiopian initiative is one of many being pursued by the CGIAR Research Program on WHEAT, which draws on the experience of lead Center the International Maize and Wheat Improvement Center (CIMMYT), ICARDA and other partners, to address the threat of wheat diseases and raise the productivity of wheat farming systems.

As the world’s population continues to grow, finding solutions for wheat farmers in target regions such as South Asia, which produces around 20 per cent of the world’s wheat, and non-traditional wheat growing countries in sub-Saharan Africa, is a priority for WHEAT. CGIAR-derived improved varieties are already grown on more than 50 per cent of the entire area sown to wheat in the developing world, which in turn accounts for two-thirds of global production.

CGIAR research activities include playing a prominent role in the Borlaug Global Rust Initiative (BGRI), which was launched with the goal of reducing the world’s vulnerability to wheat stem, yellow, and leaf rusts. Citing BGRI’s contribution to averting disaster, when Ug99, a new form of devastating wheat stem rust was discovered in Uganda in 1999, CGIAR CEO Frank Rijsberman recalls the race to develop Ug99-resistant wheat varieties before the disease spread. “CGIAR partnered with many others, in particular Cornell University, in the Borlaug Global Rust Initiative,” he said. “Today, Ug99-resistant varieties have been made available to farmers, preventing disasters on a scale affecting many millions of people.”

Successful control of stem rust – mainly through resistance breeding – is estimated to have saved farmers US$1.2 billion annually on a global scale over the past four decades. This is the equivalent of producing enough wheat to satisfy almost the entire annual calorie deficit of sub-Saharan Africa’s undernourished population.

But while various interventions have produced impressive results, all the evidence shows that the battle is not over just yet. Wheat rust is caused by deadly fungal pathogens that are constantly evolving, so it is important for scientists and producers to stay ahead of the game.

A head start for farmers

A global rust tracking system developed by CIMMYT and partners is helping them to do just that. The RustTracker information system was launched in 2008 as part of an array of early warning tools designed to help combat Ug99. A recent article in the New Agriculturist describes how RustTracker is helping to monitor Ug99 as it evolves, as well as other deadly wheat rust diseases. To date, eight closely related variants of Ug99 have spread to 11 countries, reaching as far east as Yemen and Iran and threatening South Asia.

The alerts give farmers a head start, enabling them to monitor their crops and take immediate action, using recommended fungicides if Ug99 or other forms of wheat rust are detected.

“The aim of RustTracker.org is to provide a single source of information relating to global rust monitoring activities,” says CIMMYT’s Dave Hodson. “Regularly updated information can provide rapid notifications of important pathogen changes or movements, new outbreaks, or risks of outbreaks.”

Recent alerts have been issued for large areas of Eritrea, the North-west plain zone and Northern Hill zones of India, and southern Ethiopia, where a severe, localized stem rust epidemic broke out in late 2013 after a previously rust-resistant cultivar suddenly became susceptible.

Overview Map on RustTracker.org showing Ethiopia localized stem rust epidemic
Overview Map on RustTracker.org showing Ethiopia localized stem rust epidemic

Thanks to advanced risk maps, produced and interpreted under a new collaboration initiative between RustTracker and Cambridge University, high-risk neighboring countries can now be given advance warning.

Wheat rust is widely acknowledged as a global problem, and CGIAR research is in the forefront of attempts to tackle it. A recent blog describes how wheat farmers in Kenya have benefited from new varieties developed by CIMMYT and released by the Kenya Agricultural Research Institute (KARI). These varieties are not only resistant to rust, but generate yields 10 to 15 per cent higher than local varieties.

According to CIMMYT wheat pathologist/breeder Sridhar Bhavani, eight varieties have been released since 2008 in Kenya and more than 40 Ug99-resistant varieties/advanced lines produced by the KARI-CIMMYT screening nursery in Njoro have been released globally.

From China, the world’s leading producer and consumer of wheat, comes news of CIMMYT efforts to pioneer breeding of durable resistance to stripe rust. A May 2013 workshop, jointly organized by CIMMYT and the Sichuan Academy of Agricultural Sciences (SAAS), launched a mentoring strategy to ensure that stripe rust resistant lines are released throughout the country.

China has the largest area prone to stripe rust epidemics in the world and has already been hit by two major epidemics, in 1990 and 2002, resulting in the loss of 2.65 and 1 million tonnes of grain, respectively. Given China’s importance in the world’s wheat production and consumption, any threat to the country’s wheat production has implications for global food security.

As a global call to action, the upcoming 2nd International Wheat Stripe Rust Symposium in Izmir, Turkey (28th April until 1st May, 2014), plans to bring together the world’s leading stripe rust researchers, development partners and decision-makers from stripe rust-affected countries to assess the current state of research and plan for regional cooperation on rust surveillance. The symposium is being organized by ICARDA, CIMMYT and BGRI in partnership with FAO and the Turkish Ministry of Food, Agriculture and Livestock

Back in Ethiopia, many farmers who have planted the new rust-resistant varieties have been rewarded with higher revenues, which some have invested in machinery and fertilizer, producing a knock-on effect of increased productivity, leading to improved  health care and education for the rest of the family.

One of them is Ato Beriss Felissa…

“The new wheat is fantastic. It is not vulnerable to disease and it is very profitable,” he said. “I plan to plant more of the new seeds. These new varieties are bringing us more income. We are very happy.”

Other important contributors to work in this area include the Eastern Africa Agricultural Productivity Project (EAAPP) and FAO, with funding from the African Development Bank (Support to Agricultural Research for Development on Strategic Commodities: SARD-SC/Wheat) and, as of 2012, USAID and the Durable Rust Resistance in Wheat Project (DRRW) led by Cornell University.

More information:
Success Story: Combating the threat of Wheat Stripe (Yellow) Rust (ICARDA video)
Tackling the threat of stripe rust in Ethiopia (ICARDA)
Capacity building works to combat wheat rusts (CIMMYT)
Collaborative wheat breeding for durable resistance to stripe rust in China (CIMMYT)
Science magazine: Global research to control stem rust disease saves wheat farmers losses worth US $1.12 billion per year (CIMMYT)
RustTracker
Keeping track of rust (New Agriculturist)
Borlaug Global Rust Initiative (BGRI)