How to Prepare for Soybean Rust

Stockpiling certain fungicides may not be the best option until you know the situation on your farm. Jacqui Fatka

Published on: Jul 9, 2004

July and August are the most likely months that soybean rust could penetrate U.S. soybean fields. Despite previous University of Illinois reports, no confirmed cases of soybean rust have been found north of the equator.

Although the chances of the disease arriving this growing season are less likely, producers need to be prepared by diligently looking for the disease.

Monte Miles, plant pathologist with the USDA Agricultural Research Service at the University of Illinois, explains that as the disease moves further north, over into Ecuador, the probability of getting soybean rust increases each year because of the wind currents that can carry the spores to the United States. Miles adds that without confirmed reports from Brazil's government that the U.S. is relatively safe.

Because of South America weather conditions, soybean rust has basically stalled south of the equator. However, soybeans planted north of the equator in Brazil are planted during the same season as the United States. Whereas those planted south of the equator are planted in the U.S. winter season. Miles explains that the spores are waiting to have a host, which with the differing seasons is preventing the rust from being spread to the north.

Stockpiling isn't the answer

Fungicides have been found to be very effective against reducing the harmful yield loss of soybean rust. Researchers are still examining the best way to apply the coverage. Miles says higher volumes and slower speeds with a spraying rig is expected to work well.

Kent Smith from the USDA's Office of Pest Management Policy says that sixteen of the major 30 soybean producing states have signed a Section 18 emergency exemption for fungicides approved if soybean rust is found. "Growers should be able to respond right away which is one reason for the Section 18 exemptions," Smith says, adding that it allows fungicides to get out in the field immediately.

Miles reminds producers that all fungicides are not created equal. "When it comes time to spray, [the disease] is very manageable if you use fungicide," he says. "You're going to need to understand what level of disease you have though. You're going to have to become familiar with the fungicides.

"Look at what fungicide will control the disease and at what time it will be helpful," Miles adds. "If you don't know if that fungicide is going to be effective, why stock pile it?"

Researchers are worried that farmers are stocking up on chemicals that have a short shelf life. Yang says he's heard of farmers purchasing tens of thousands of dollars in fungicides in anticipation of the disease. "Some may be stocking chemicals they won't need in the near future," Iowa State University researcher X.B. Yang says.

What to do now

Farmers need to remember soybean rust is a manageable disease, United Soybean Board Communications Committee Chair David Durham says. Producers need to prepare themselves by being educated. If you aren't scouting the fields, find a crop consultant who can he says.

"The best thing we can do as producers is to prepare and not become overly excited," he says, adding to diligence is important before the situation does arrive.

To order a soybean rust diagnostic guide, visit Or visit APHIS's Soybean Rust Site for more information.