Tests confirmed soyabean rust disease has spread throughout Louisiana and into Mississippi, the US Agriculture Department said on Tuesday, adding to fears the fungus could rapidly infect more Southern states. The first case of soyabean rust on the US mainland was confirmed last week at two Louisiana State University research plots near Baton Rouge. The wind-borne disease does not harm humans, but can cut soyabean crop yields by up to 80 percent.
"Three of the four samples taken in Louisiana, and the sample collected in Mississippi tested positive," USDA's Animal and Plant Health Inspection Service said in a statement.
That means the fungus has now been found in three Louisiana parishes - St. Mary, St. John the Baptist, and Iberia - and one county in neighbouring Mississippi.
The USDA did not say how many acres were infected.
On the commodities market, soyabean futures for January delivery at the Chicago Board of Trade ended higher on concerns over soyabean rust. At the close, the January contract was up 4-1/4 cents at $5.40 per bushel, while contracts for delivery in August and September of 2005 - the key harvest months for next year - rose by more than 10 cents a bushel.
Soyabean rust is characterised by reddish brown lesions on soyabean plants, and makes them shed their leaves.
The fungus has spread from Asia to Africa and into Latin America, devastating crops in many countries. The USDA had warned farmers for two years that the disease was virtually certain to creep into North America. Hurricane Ivan blew the fungus into Louisiana from South America in September, according to the USDA.
Some experts say the fungus can travel 20 to 30 miles a day, depending on wind and weather conditions, and could spread to large soya-producing states in the Midwest by the 2005 growing season.