Published on 02/24/05

Farm experts to monitor new soybean disease

By Brad Haire
University of Georgia

University of Georgia farm experts will begin planting soybean plots throughout Georgia next month to act as early detectors for an aggressive crop disease first reported across the Southeast last fall.

Asiatic soybean rust was reported in the United States in November. Tropical storms in September are believed to have picked up spores in South America and delivered them to Southeastern states.

It was first reported in soybean research plots in Louisiana. Later, it was identified in farm fields in Alabama, Arkansas, Florida, Georgia, Mississippi, Missouri, South Carolina and Tennessee.

This year?

The disease hit late in the 2004 growing season. It didn't cause any damage to the crop. But Southeastern soybean farmers may not be as lucky this year, said Bob Kemerait, a plant pathologist with the UGA Extension Service.

"It's not guaranteed," Kemerait said. "But it's very likely that it will hit us this year."

Asiatic rust is a tropical fungal disease. Cold temperatures kill it. It probably didn't survive Georgia's winter, he said.

"But it's likely that it did survive in south Florida or in the Caribbean," he said. "It could be reintroduced very quickly."

It's carried by wind, he said, and can spread as fast as 300 miles a day. The disease attacks a plant's leaves, reducing yields or killing the plant.

Control early

The UGA Extension Service will monitor 15 to 20 plots on research stations and farms across Georgia, said Phil Jost, a UGA Extension agronomist.

"We hope they will be like canaries in the mineshaft," Jost said, "where we will detect the disease first on these plots before it's picked up in growers' fields."

The disease can be controlled with fungicides, he said. "But the key will be to control it on time and quickly."

Georgia growers usually don't spray soybeans with fungicides. But they'll have to, he said, if this disease gets in fields. But it'll cost $20 to $30 per acre. This could eat up any profit for some farmers.

"Soybeans have traditionally been a cheap and easy crop to grow for Georgia," Jost said. "This rust changes both of those."

Soybeans are a more highly valued crop in the Midwest, where most of the U.S. crop is grown. Kemerait and Jost will coordinate and share information from Georgia's Asiatic soybean rust monitoring program with the U.S. Department of Agriculture, other Southeastern states and research institutions in the Midwest. If the disease shows up, farm officials there can implement their control programs.

Georgia farmers planted 270,000 acres of soybeans last year. But they'll probably plant fewer acres this year, due to the rust threat and lower expected prices, Jost said.

The disease can hurt other Georgia crops, such as snap beans and Southern, pole and English peas. But they're not as susceptible as soybeans, said David Langston, a UGA Extension plant pathologist. If left unchecked, though, it could cause problems.

Georgia's pea and bean crop was worth $77 million in 2003. Snap beans accounted for about $60 million of that. Georgia ranks second in the United States in snap bean production. Most of Georgia's snap beans are sold for fresh markets.

Georgia farmers who plant peas and beans already spray their crops at least once for other fungal diseases, Langston said. This should also take care of Asiatic soybean rust.

But farmers need to watch for the disease, he said, and be ready to respond with more fungal sprays if it gets a foothold in a field.

Brad Haire is the former news editor with the University of Georgia College of Agricultural and Environmental Sciences.