Sunday, April 20, 2014
Wheat rust: The fungal disease that threatens to destroy the world crop
Scientists are warning that wheat is facing a serious threat from a fungal disease that could wipe out the world’s crop if not quickly contained. Wheat rust, a devastating disease known as the “polio of agriculture”, has spread from Africa to South and Central Asia, the Middle East and Europe, with calamitous losses for the world’s second most important grain crop, after rice. There is mounting concern at the dangers posed to global food security.
Experts have been aware of the threat since a major epidemic swept across North America’s wheat belt in the 1950s, destroying up to 40 per cent of the crop. Since then, tens of millions of pounds have been invested in developing rust-resistant varieties of the grain. However, an outbreak in Uganda in 1999 was discovered to have been caused by a virulent mutation of the fungus. There has been alarm at the speed at which further mutations have subsequently developed and spread across continents.
Plant scientists in Britain estimate the latest developments mean that 90 per cent of all current African wheat varieties are now vulnerable to the disease. Last year, Germany witnessed its first outbreak of stem rust in more than 50 years. The outbreak was spurred by “a period of unusually high temperatures and an unusually late development of the wheat crop due to cold spring and early summer temperatures”, explained Kerstin Flath, of Germany’s Federal Research Centre for Cultivated Plants.
A further outbreak occurred in Ethiopia last November, with farmers losing on average 50 per cent of their wheat crop; the worst affected lost up to 70 per cent. Experts met in Mexico last month to discuss the threat. Work is under way to examine the different strains, to identify similarities. According to Dr David Hodson, of the International Maize and Wheat Improvement Center in Addis Ababa, the disease’s threat lies in its ability to cause “large- scale destruction in a very short period of time over very large cultivated areas”. Rust epidemics could be compared to a forest fire, Dr Hodson said. Once it manages to gain ground it can very quickly spread out of control. The fungus reproduces millions of wind-borne spores, each of which is capable of starting a new infection. Fazil Dusunceli, of the UN’s Food and Agriculture Organisation, said that the fungal disease, along with drought, are major challenges to wheat production globally. ... read more: