ISU: Soybean Rust Won't Hit Midwest this Year

Researchers' model says weather patterns unlikely to carry soybean rust to the Midwest by this growing season. Compiled by staff

Published on: Jun 24, 2004

Iowa State researchers are concerned that there is too much anticipation for soybean rust to hit the Midwest causing overreaction on a disease that may not hit the region this growing season. Although University of Illinois research indicates soybean rust will reach the United States this year, Iowa State scientists indicate that it is unlikely it will affect the continental United States and impact soybean production this year.

X.B. Yang, a professor of plant pathology at Iowa State, and other experts agree that the fungal disease will eventually arrive but is unlikely to be carried to North America by winds this year. "The disease would take a long time to travel through the Amazon basin," Yang says.

The latest computer models from the University of Illinois indicate that Asian soybean rust has most likely already spread to soybean-growing areas in Brazil and Venezuela located north of the equator. Aerobiologist Scott Isard from the Department of Geography at the University of Illinois says, "If it's already established there, we could even see rust in the U.S. as soon as the current growing season and certainly no later than a year or two down the road."

Yang and other experts have developed models that predict how the pathogen might travel if wind-borne spores land in the southern region of the United States. "A model is built by inputting environmental information," Yang says. "This helps us predict what will happen with diseases just like a meteorology forecast predicts the weather. We want to forecast what will happen in Iowa as well as other states in the north central region."

Greg Tylka, plant pathology professor at Iowa State, also believes that rust will not land in North America this growing season. And if it is carried by winds to the southern United States it would not appear in the Midwest until later in the growing season. "It likely won't arrive until August or later because it will take time to get established," Tylka says. "If this disease shows up with only a few weeks of the growing season left, it's not going to cause as much damage as it would if it were present throughout the season."

Tylka says he's concerned about the apprehension over a disease that hasn't been found on this continent. "This is the first time I've seen people so anxious before a problem shows up. I'm afraid that some are on the verge of overreacting," Tylka says.

"We want to emphasize that there a lot of people paying attention to this, that we have a good system to check for soybean rust and producers should be very cautious about any unverified information they hear," he says.

Rust can be treated with fungicides and 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. "We believe that it will be very unlikely to have rust infestation this season in Iowa," Yang says. "Some may be stocking chemicals they won't need in the near future."