By Brad Haire
University of Georgia
Asiatic soybean rust was positively identified in Georgia today, said Bob Kemerait, a plant pathologist with the UGA Extension Service. The first case of the disease in the continental United States was in Louisiana and announced on Nov. 10. It has since been identified in Mississippi and Florida, too.
The disease attacks a plant and defoliates it, killing the plant or severely reducing yields.
It's an aggressive disease that infects and produces spores quickly. "If it spreads, it could affect a large portion of the soybean crop in the United States," he said.
Georgia's 2004 soybean crop is too far along in growth for the disease to cause much damage this year, Kemerait said. Georgia farmers planted about 250,000 acres of soybeans this year, about 60,000 acres more than last year.
The confirmation came from a sample in Seminole County taken by UGA Extension Service agent Rome Ethredge, Kemerait said. But it is believed to be widespread across the state.
Tropical deliveryIt's likely that Hurricane Ivan, which skimmed the coasts of South America around Sept. 13, picked up the disease and delivered it to the Gulf Coast states. The resulting wet, windy weather from other tropical storms allowed the rust to spread.
The leaves of a plant infected with the disease will appear dried and dead. But soybean plants across the state have looked this way for sometime now because of natural defoliation this time of year.
That's why the disease wasn't identified earlier, he said. After the confirmation in Louisiana, UGA Extension Service agents and other agricultural officials began surveying Georgia soybean fields for the disease.
Costly diseaseAsiatic soybean rust has hurt soybean production in Asia, Australia and Africa. By 2000, it was in South America. It cost Brazilian farmers an estimated $1 billion in damage and control measures in 2003.
Asiatic soybean rust doesn't hurt humans or affect other major Georgia row crops, such as peanuts and cotton. But it does affect Southern peas, pole, lima and snap beans, which are grown in Georgia. It also attacks and defoliates kudzu, one of Georgia's most infamous invasive plants.
No soybean varieties are resistant to this rust, Kemerait said. But fungicides can control it. Soybeans are a higher-value crop in the Midwest, so farmers there protect them with fungicides.
Georgia growers usually don't spray fungicides on soybeans. But this will likely have to change, he said.
"There's no doubt we can handle Asiatic soybean rust in America," Kemerait said. "The concern is how much additional production cost will it take."
Asiatic soybean rust is a tropical disease. Freezing temperatures kill it. It could spread in the United States during the summer, but it will have to fall back during winter to places that don't freeze, such as south Florida and Texas.
Now that it's in the United States, though, it will stay. "We won't eradicate this disease," Kemerait said. "We'll just have to contain and control it."
Response planKemerait, UGA plant pathology department head John Sherwood and Extension Service soybean agronomist Phil Jost are working with the U.S. Department of Agriculture Animal and Plant Health Inspection Service and the Georgia Department of Agriculture to form a first-response plan for Georgia agricultural crops.
UGA Extension Service county agents are training to identify and respond to this and other diseases.
Soybeans are sometimes boiled with salt like Deep-South peanuts in Japan and other places. But in most of the United States, the high-proteins are used mostly in highly processed forms.
Textured vegetable protein, soy lecithin and vegetable oil from soybeans are key ingredients in meatless burgers, milk and cheeses, infant formulas, chocolate candies and countless other foods.
Soybeans are used to make nonfood products, too, such as soap, cosmetics, resins, plastics, inks, crayons, solvents and biodiesel fuel.
(Brad Haire is the former news editor with the University of Georgia College of Agricultural and Environmental Sciences.)