Asian Soybean Rust spores, brought to motion by recent tropical storms, are affecting parts of the United States but are unlikely to move closer to Iowa’s soybean crops.

Soybean rust is a fungus that produces spores, the seeds of the fungus, and are dispersed into the wind. The wind then carries them across the country to land in fields where it has a susceptible host.

“At the moment, the disease has been identified east of Mississippi and the winds we get in Iowa come from Louisiana and Texas,” said Alison Robertson, assistant professor of plant pathology. “The disease is too far east, there isn’t very much of it.”

There have been reports of up to 80 percent field loss in South Africa and Brazil as a result of the disease, Robertson said. In most cases if the disease is caught early enough and fungicides are applied, it can maybe cause 10 percent field loss.

“Those in South Africa were taken by surprise, no one was prepared,” she said. “The rest of the world is very impressed with how prepared we are.”

Although it could be blown up to Iowa from Kansas, the disease’s history shows that it moves as a front so it could be seen moving up through Alabama and Tennessee, Robertson said.

Soybean rust was first spotted in the United States on Nov. 10. 2004.

Reported areas of soybean rust activity in Alabama and Georgia are unlikely to be effective sources of rust spores for northern states because of limited rust activities, according to the Integrated Crop Management Web site.

In order to prevent soybean rust, people have been looking for crop disease activity around Iowa farms every week, Robertson said.

No samples of rust have been found.

Producers have been advised to wait until soybean rust is confirmed north of Interstate 70, which runs between Kansas City and St. Louis, before making decisions on applying preventative fungicide treatments, according to the ISU Web site.

Robertson said guidelines need to be followed when deciding if fungicides are needed. Fungicides have a label that is registered for use against soybean diseases. The guidelines would be adjusted as the season progresses based on crop conditions, weather forecasts and soybean rust movement in the south.

Iowa applied to get a Section 18 of the federal label, which has to be approved by the Environmental Protection Agency.

“Section 18 is an emergency exemption to be specifically used for Asian Soybean Rust management,” Robertson said.

There are strict guidelines when using the fungicides.

“The fungicides can only be used three times during the season and you have to carry the Section 18 with you … when you are spraying fungicides. You also need to record what you use and how much of it,” she said.

It is unlikely that soybean rust will be found in soybean fields before mid-August, according to the Integrated Crop Management Web site. If the rust is found in Iowa after mid-August, the disease is unlikely to cause any significant economic damage.