Researchers are putting up a strong fight against devastating wheat pathogens and have made progress in tracking and controlling disease outbreaks, helping to protect crops from East Africa to South Asia. But the wheat fields of central Asia, including China — the world’s largest wheat producer — are still vulnerable, agricultural scientists will warn at an international conference in Beijing next week.
Wheat rusts, including the devastating Ug99 stem-rust fungus, are mutating and spreading across the globe (see Nature’s previous coverage here and here). In 2010, scientists discovered that two new forms of Ug99 were on the move from their origins in Uganda and had spread to South Africa for the first time. And they fear it could spread further.
“It is highly likely that some of the virulent new strains related to Ug99 will eventually be carried across the Middle East and Central Asia and into the breadbaskets of Pakistan, China and India,” says Dave Hodson, a senior scientist at the International Maize and Wheat Improvement Centre (CIMMYT), a leading research centre based in El Batan, Mexico.
To fight the spread, Hodson has led efforts to develop a computer system to track the global movements of wheat pathogens with the help of data provided by farmers and scientists from fields and laboratories. The ‘rust-tracker‘ can now monitor 42 million hectares in 27 developing countries, Hodson will tell researchers at the Borlaug Global Rust Initiative, which runs 1–4 September in Beijing.
Over the past 18 months, the Global Rust Reference Centre, a wheat-pathogen-typing lab at Aarhus University in Denmark, has expanded its remit to accept suspected samples of stem rust from around the globe at any time of year. Previously, the handful of labs around the world able to analyse wheat-rust samples would accept international samples only during winter, when the pathogen is less likely to spread.
“They are afraid it could escape,” says Ronnie Coffman, a plant geneticist at Cornell University in Ithaca, New York, but this constrained researchers’ ability to monitor the pathogens.
Scientists have developed at least 20 new wheat varieties with multiple genes resistant to Ug99 and other rust pathogens, and they have helped introduce these into farmers’ fields in eight high-risk countries, including India, Kenya, Nepal and Afghanistan.
“The only manageable solution for farmers who cannot afford fungicides when rust hits is to replace their crop with new resistant varieties,” Coffman says.
Planting just 5% of a nation’s wheat fields with seed from resistant varieties is sufficient to provide enough seeds to replace the nation’s crop within a year if Ug99 should appear, he explains.
The eight countries are expected to pass the 5% mark in the 2012–13 growing season.
But Central Asian nations, including China, are paying insufficient attention to wheat pathogens, leaving themselves open to attack, Coffman warns.
Li Jiayang, vice-minister of agriculture and vice-president of the Chinese Academy of Agricultural Sciences, warned that cereal diseases could lead to an overall decrease in food production of up to 30% in serious cases, reports ChinaDaily.com, online Chinese newspaper.