Devastating wheat rust spreading rapidly, experts warn

Aggressive new strains of a wheat-attacking fungus have wiped out up to 40 per cent of harvests in Central Asia, the Middle East and North Africa.

Wheat stripe and stem rust diseases are spreading rapidly and dodging farmers' defences by evolving quickly, scientists and policymakers said at the International Wheat Stripe Rust Symposium held in Syria earlier this month (18–21 April). Experts said that the world may be witnessing the most rapid spread of an important crop pathogen so far.
Farmers in affected developing countries, which include Egypt, Ethiopia, Iran, Kenya, Morocco, Syria and Yemen, are struggling with economic hardship because wheat supplies 40 per cent of people's daily calorie intake in many areas.
"Wheat stripe rust infection can spread from Uganda to West Asia in just 24 hours," said Michael Baum, director of the Biodiversity and Integrated Gene Management Program at the International Center for Agricultural Research in the Dry Areas (ICARDA), which organised the meeting, attended by scientists and policymakers from 31 countries.
There is a stark difference between its consequences in poor and rich countries, said Baum. Last year Syria lost up to half of its wheat to the infection whereas neighbouring Turkey, a richer country, lost none.
In Syria, monitoring is weak; three-quarters of the crop consists of a single variety; and there is not enough fungicide available, he said. Turkey, in contrast, has good monitoring; a wide variety of plants, some of which are resistant to the current rust; and substantial supplies of fungicide.
"Syria, Iraq, Morocco, Ethiopia, and Lebanon are the countries most threatened by yellow [stripe] rust this year," Wafa El Khoury, coordinator of the Wheat Rust Disease Global Programme at the UN Food and Agricultural Organization, told SciDev.Net.
He said that farmers must be continually supplied with a range of new resistant varieties.
Every country needs a surveillance system, said Kumarse Nazari, a cereal pathologist at ICARDA. Farmers need training so they can spot, and deal with, the disease; and no single variety should form more than a quarter of the crop.
"Developing a new resistant variety is not an easy procedure — it could take about ten years," said Osman Abdalla El Nour, a wheat breeder at ICARDA. "Add to this, in developing countries, the time that official organisations could take to approve the variety and breed it."
Ruth Wanyera, a researcher at the Kenya Agricultural Research Institute, said: "In the past resistance [to rusts] became ineffective in less than six years, but now newly introduced resistant varieties lose their resistance within a shorter time — even the latest releases have succumbed to yellow rust infection."
Several countries reported on what they are doing against the diseases.
Syria has purchased eight forecasting systems, expected to be operating by 2012, that will warn of stripe rust risk, said Fawaz Azmeh, a researcher at the Syrian National Commission for Biotechnology.
By using several different resistant varieties, Egypt has not been heavily affected this season, said Omima Abd Ellatif, a researcher at Egypt's Agricultural Research Center.
And in Morocco, many resistant varieties are available to farmers, according to Abad Andalusi, head of plant protection at the National Institute for Agricultural Research. But farmers cannot afford fungicides so if infection gets a hold "there would be a great loss".

Story Source:
ScidevNet / http://www.scidev.net/en/