It looks like farmers in the Peoria area will be spending more time in the field during the 2005 growing season. Not necessarily on a tractor, but hands-on scouting. Asian Soybean Rust was detected in Baton Rouge, La., in mid-November. In less than a month, the disease was diagnosed in eight more states, including Alabama, Arkansas, Florida, Georgia, Mississippi, Missouri, South Carolina, and Tennessee.
In Missouri, it was discovered only 30 miles south of Cairo, Ill. Fortunately, the 2004 soybean crop was mature, and harvest was practically finished by the time it was found.
Asian Soybean Rust is the more aggressive of two soybean rust species and is native to Asia and Australia. It's spread by wind-borne spores over long distances. Symptoms of the disease include lesions on the lower leaves of plants that increase in size and change from gray to tan or reddish brown on the undersides of the leaves. Defoliation can rapidly weaken the plant and reduce yields.
American farmers have been warned about this disease for several years now. It seemed as though everyone was guessing about when it would arrive in the United States. South American farmers in Brazil and Argentina have been battling its devastating effects since 2001. Yield losses on soybeans for farmers in the Southern Hemisphere have reached 80 percent.
The culprit believed to have brought Asian Soybean Rust to the U.S. is Hurricane Ivan. Along with tremendous winds and rain, Hurricane Ivan is being blamed for providing a free ride for some tiny soybean rust spores to the Gulf Coast states.
Corn Belt states such as Illinois have a climate advantage when it comes to a rust disease outbreak, however. Asian Soybean Rust spores can't overwinter in freezing temperatures. This fact alone should help warm the hearts of Peoria area farmers during some chilly winter temperatures.
The next three seasons will play a role as to if and when a soybean rust outbreak occurs in Illinois during the 2005 growing season. One question to be answered during this winter season is how far south it'll freeze. As far as rust prevention, a shot of cold Canadian air would be welcome. If rust spores do survive the winter season in the southern U.S., they'd have to hitch a ride on southern currents blowing north this spring.
Every spring, warm southerly breezes have blown up through the Corn Belt states. These currents bring cutworm moths. The severity of cutworms depends on the timing and strength of the southern currents. Similar circumstances likely would affect the severity of Asian Soybean Rust.
Currently, there are no rust resistant or tolerant soybean varieties. Research is ongoing, but it still looks like it will be five to 10 years before varieties with rust resistance are available. Foliar fungicides, currently the only soybean rust control measures, cost farmers $10 to $25 per application.
Weather extremes, new diseases, herbicide resistant weeds-it'll just be another normal growing season for farmers in 2005. This last year was very rewarding-but not normal. IBI