Soybean South


Rust Update

In 2008, soybean rust was identified across the Mid-South and Southeast.
However, because it appeared late in the season, the disease did not
cause any significant yield losses.

By Carroll Smith

In 2004, Asian soybean rust spores rode into the United States on the coattail of Hurricane Ivan relatively late in the year. However, the mere presence of rust in our country immediately made Page 1, above-the-fold news because it was known for devastating soybean crops in countries like Brazil.

Since 2004, USDA, university personnel and industry have worked closely and diligently to monitor rust in the soybean-growing states, get fungicides registered, hold meetings, provide educational tools and step up work on developing rust-resistant varieties. So far, soybean rust has not caused significant losses in the United States.

Mid-South rust report
Tom Allen, the Delta Extension plant pathologist with Mississippi State University, came on board last year and now has statewide responsibilities for soybean rust. Like specialists in every state, he coordinates the sentinel plots, scouts for rust and participates in a weekly conference call to update the nation on the rust situation in Mississippi. He also is responsible for entering all pertinent information about rust in the state for the public Web site –

For example, when rust is found in a Mississippi county, Allen reports it to the Web site, and that county turns “red” on the national map. “Green” denotes areas that have been scouted, but no rust was found. The upside of this tool is that it alerts producers in counties where rust has been identified. The downside is that if one spot of rust is found on one leaf, the entire county turns red, and some farmers panic.

“If you look at the map, it looks like we found a lot of rust in Mississippi this year, which is not necessarily the case,” Allen says. “We found rust in a lot of places, but there was no damage to the crop in any of those locations where we identified the disease.”

Another helpful tool for farmers in the Mid-South is the Soybean Rust Hot Line (866-641-1847), which is sponsored by BASF and the Mississippi Soybean Promotion Board. Anyone can call in and get updated information on rust, where it has occurred and what the current suggestions are for Arkansas, Louisiana and Mississippi.

Rust updates, sponsored by the Mississippi Soybean Promotion Board, also are announced on public radio stations.

Southeast weighs in
John Mueller, Extension soybean pathologist and director of Clemson University’s Edisto Research & Education Center, reports that the only significant rust that occurred in the Southeast this year was in the Florida/Georgia border area.

“Rust moved up toward Tifton, Ga., but between Tifton and South Carolina, there was very little rust at all,” he says. “Rust really didn’t come into South Carolina until September. We eventually found it in 15 counties, but it was fairly late in the season and didn’t cause any yield loss to speak of.”

Mueller says the drought conditions that Georgia and South Carolina experienced during the first part of the summer held back the rust. When it did begin to appear, growers in the Southeast began spraying fungicides to protect their crops.

“Any rust that came into the South Carolina or North Carolina area probably hit fields that had been sprayed, so the chances of it developing into anything damaging were pretty slim,” he adds.

Like their counterparts in the Mid-South, plant pathologists in the Southeast publish newsletters that keep growers up-to-date on the rust situation and report any findings to

Another tool that was developed to educate Southeastern producers about rust is a guide titled “Soybean Rust Management in the Mid-Atlantic Region.” Version 1 was published in 2006, followed by an updated version in 2008. Specialists from Virginia Tech, Clemson, North Carolina State and Georgia contributed to the guide, and the South Carolina Soybean Board (SCSB) used checkoff dollars to print it.

“Everyone has been receptive and appreciative of the information,” Mueller says. “We gave out several thousand copies, and the information will still be pertinent next year.”

To view the guide online, visit and click on Research. To obtain a hard copy, call the SCSB at (803) 734-1767.

Soybean Rust Frequently Asked Questions

One of the most frequently asked questions from farmers about soybean rust is, “Why are you still out looking for something that may not be causing any problems?”

Tom Allen, Delta Extension plant pathologist with MSU, notes, “This year the elements seemed to stack up nicely for a major rust infection to occur over a large geographic area. However, rust appeared
so late in the season that it didn’t do any damage.”

Billy Moore, MSU Extension plant pathologist emeritus, adds, “Soybean rust is a cool- weather disease, which also requires moisture. In fact, it requires about 6 to 6 and 1/2 hours of moisture for the spore to germinate and subsequently cause an infection.

“Since rust came into the United States, the growing months have been hot and dry, so rust has not been a
factor,” he says. “It’s not until the fall of the year that the disease has taken off.

“However, if we do experience conditions favorable to rust when the plant is in the reproductive stage and very susceptible to the disease, it can be a very destructive pathogen. Even though we haven’t experienced losses from rust yet, it’s not just a lot of hype. That’s the reason we keep looking.”

Another frequently asked question about the disease is, “If rust is found in one of my fields, will it be in that same field next year if I plant soybeans there?”

Allen says, “No, not necessarily, because the spores have to overwinter somewhere and then be blown in the next year.”

To ask a question about rust in Louisiana, Mississippi or Arkansas, call the hot line at 866-641-1847.