Asian Soybean Rust Confirmed On Louisiana Soybeans

Clayton Hollier, Padgett, Guy B., Lanclos, David Y., Benedict, Linda F.  |  7/27/2006 12:03:38 AM

News Release Distributed 07/26/06

LSU AgCenter scientists confirmed Wednesday (July 26) that Asian soybean rust was found on soybeans in Rapides Parish.

This is the first finding of the disease on soybeans in Louisiana for 2006. It had been found about a month ago on kudzu, a plant that can host the disease, in Iberia and Lafayette parishes.

The discovery on soybeans came in the central part of the state in a sentinel plot on the LSU AgCenter’s Dean Lee Research Station in Alexandria. The plot is one of 15 in the state planted early to give scientists a heads-up in case of a disease outbreak.

"It’s been raining – providing the warm, humid conditions this disease likes," said Dr. Clayton Hollier, LSU AgCenter plant pathologist. "We suspect if it’s been found here, it is also in other soybean fields in the state."

The recommendation to farmers is that they treat vulnerable fields with a fungicide to halt the disease’s growth. They can get the fungicide recommendations from any LSU AgCenter agent or on the AgCenter’s Web site (

"This must be done on a field-by-field basis, based on the growth stage in the field and any treatments that have already been applied," said Dr. David Lanclos, LSU AgCenter soybean specialist. "We’re not recommending blanket spraying. Producers can contact anybody at the LSU AgCenter, and we’ll help them with a plan to protect their crops."

Lanclos said up to 70 percent of the total soybean acreage in the state (830,000 acres) already has reached a maturity stage in which the disease, even if it occurs, will not hurt yields. In those cases, beans "already have been set."

Unfortunately, the rest of the soybeans in the state were planted later, and beans are still forming, he said.

"There are nine parishes in the state that traditionally plant their beans later," Lanclos said. "These soybean fields are particularly vulnerable."

The disease causes defoliation, which stops photosynthesis and thus plant growth.

The nine parishes where soybeans generally are planted later are in the south central and southwestern parts of the state and include Acadia, Avoyelles, Beauregard, Evangeline, Jefferson Davis, Pointe Coupee, Rapides, St. Landry and St. Martin.

Hollier, who analyzes about 1,500 suspect leaves taken from across the state each week in his lab, said the leaves from the plot where the disease was confirmed were thick with disease spores.

"Several sporulating pustules were found on 75 percent of the leaves taken from the plot," Hollier said. "This means the disease was well on its way."

Asian soybean rust, which has the potential to devastate soybean yields because of its ability to spread fast, already has been confirmed on soybeans in Alabama and Georgia in the past few weeks, Hollier said. Scouting efforts are under way throughout the United States.

Dr. Boyd Padgett, an LSU AgCenter plant pathologist at the Northeast Research Station in St. Joseph, said soybean farmers can call a toll-free number for updates about Asian soybean rust, and that number is (800) 516-0865.


Clayton Hollier at (225) 578-4487, (225) 281-9365 (cell) or
David Lanclos at (318) 473-6530, (318) 308-5386 (cell) or
Boyd Padgett at (318) 435-2157 or
Linda Foster Benedict at (225) 578-2937 or

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