Compared with 2007, this year has been relatively quiet as far as the spread of Asian soybean rust is concerned. Until recently the weather patterns in the South were not suitable for soybean rust, but with Tropical Storms Edward and Fay and Hurricane Gustav that has changed. Rust has developed rapidly in Mississippi, Louisiana and Texas, and has also been found in Southern Arkansas earlier this week.
"Disease is building up in the South and so if we do get a weather pattern that moves wind currents up in the next week or so the disease could be moved into Missouri and the rest of the Midwest," says Allen Wrather, a plant pathologist at the University of Missouri's Delta Center in Portageville, Mo. "Hurricane Ike could be that weather pattern, we just don't know yet where it's going to hit the coast and where it will move once that happens."
According to USDA meteorologist Brad Rippey the official track of the hurricane has it hitting the Texas coast this weekend in the vicinity between Corpus Christi and the Texas-Louisiana border. Rippey says conditions are favorable for re-intensification once Ike hits landfall.
"Historically the spore that have arrived in the Midwest have been coming from the Texas, Louisiana, South Arkansas, Mississippi territory, not from Florida and Georgia," Wrather says. "So since it is currently building up in those states to the south of Missouri and other parts of the Midwest there could be the potential for problems."
The Midwest probably won't know whether or not rust will be a problem for another 14 to 21 days because Ike hasn't hit the coast yet, and Wrather says that is good news for soybean producers.
"In 21 days will be the first of October and by then almost all of the soybeans in Missouri and more than likely most of the rest of the states in the Midwest will be in the R6 growth stage," says Wrather. "Rust that develops at that stage will probably not damage the plants sufficiently to suppress yield."
While beans planted in May are beyond the stage where they're sensitive to rust, a lot of beans weren't planted until June or July this year because of wet conditions. Those are the soybeans that are at risk should rust develop in the next 10 to 14 days.
"That's why we are still very concerned about where rust is developing, how rapidly the weather patterns might develop to move it further north because our efforts are focused on when rust first starts to develop," Wrather says. "Last year rust showed up in the southeast and southwest parts of Missouri in the later part of September, but there were very few soybeans left that were still sensitive. That's different this year, we have a good many acres that are still sensitive because they were planted in late June and early July."
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