Asian soybean rust has not yet been found in Missouri this year, and this is good. I don’t expect rust will cause any damage to soybean in Missouri even if it does develop this year because the growing season is almost over. Rust has developed on soybean in Missouri during September and October in previous years when spores were moved from the southern USA to our state, but the disease did no damage because the soybean crop was almost mature by then. Rust spores may have been moved from the southern USA to Missouri last week by tropical storm Isaac. As a result, symptoms may be found somewhere in Missouri in about 2 to 3 weeks. However, there were few spores in the south available for movement north because this disease has not been a serious problem on soybean in the southern USA this year. In 2009, soybean rust was severe in the southern USA, and a tropical storm moved spores from there to our area around September 11. Diseased plants were found in southeast Missouri about two weeks later. This is not the situation this year. I expect some symptoms of rust may be observed on Missouri grown soybean in September or October this year but do not expect any damage. Please call me if you have questions about this situation. I am most accessible by calling my mobile phone, 573-379-0259. More information about the spread of rust in the USA is available at www.sbrusa.net.
REVISED: August 31, 2012