A fungal disease of soybeans first reported in Japan in 1902 has spread across the planet and devastated crop yields. The fungus — called soybean rust — reached Africa in 1996 and arrived in South America five years later. In China and other parts of Asia, the disease has reduced soybean yields by up to 80 per cent, and it cost Brazilian farmers US$2 billion last year. In September, hurricanes carried spores of the fungus on to North America.
In this article in Science, Erik Stokstad reports on international efforts to tackle soybean rust. Researchers at the US Department of Agriculture have tested 17,000 types of soybean in the department's collection to see if any are resistant to the pathogen. Although none was entirely resistant, 500 suffered reduced symptoms. The researchers have sent 180 varieties to collaborators in China, Brazil, Paraguay, Thailand, and Zimbabwe to see how they fare under local conditions.
Other approaches include looking for resistance to the fungus in other bean species, with the aim of genetically modifying soybeans to protect them from infection. Researchers are also developing a handheld sensor that would detect the pathogen in the field. And, in Brazil, satellite data has been used to detect the disease by analysing patterns of leaf loss.
Reference: Science 306, 1672 (2004)