By Brad Haire
University of Georgia

A soybean disease has caused major problems for farmers in South
America. And U.S. farmers need to be ready to handle it when it
arrives here, says a University of Georgia expert.

Asiatic soybean rust attacks a plant and defoliates it, severely
reducing yields or killing the plant, said Bob Kemerait, a plant
pathologist with the UGA College of Agricultural and
Environmental Sciences.

“This rust is an impressive and aggressive disease that infects
and produces spores very quickly,” Kemerait said. “If it
spreads, it could affect a large portion of the soybeans in the
United States.”

On the move

The disease has been on the radar screen of the agricultural
world for some time now. It has hurt soybean production in Asia,
Australia and Africa. By 2000, it had jumped the Atlantic Ocean
and landed in South America. It cost Brazilian farmers an
estimated $1 billion in damage and control measures in 2003.

“It went very quickly from not being a problem to being a major
problem in Brazil in about two years,” Kemerait said.

Asiatic soybean rust was reported last month to have jumped the
equator into Colombia. Models predict it will keep moving north
and eventually enter the United States, possibly through
Mexico.

A storm like Hurricane Ivan, which skimmed the coast of South
America earlier this week, could pick it up and give it a much
quicker airlift, he said.

Handle at a cost

No soybean varieties are resistant to this rust. But fungicides
can control it, Kemerait said. 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 would have to change if this disease entered the state.

“There’s no doubt we can handle Asiatic soybean rust in
America,” he said. “The concern is how much additional
production cost will it take.”

Kemerait, UGA plant pathology department head John Sherwood and
Extension Service soybean agronomist Phil Jost met this summer
with representatives of 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.

UGA Extension Service county agents, along with other farm
experts in the state, will train to identify and respond to the
disease when it arrives.

Asiatic soybean rust has at least one natural flaw that will
help U.S. growers. It’s 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.

But once it gets to the United States, it will probably
stay. “We won’t eradicate this disease when it gets here,”
Kemerait said. “We’ll just have to contain and control it.”

Other major Georgia crops aren’t at risk to the disease. But one
of Georgia’s most infamous plants, kudzu, could be in trouble.
The disease attacks and defoliates kudzu much as it does
soybeans, Kemerait said.

Georgia farmers grew about 250,000 acres of soybeans this year,
about 60,000 more than in 2003.