Released September 12, 2008
LONOKE, Ark. - Poring through hundreds of soybean leaf samples and spending hundreds of miles on the road a day is price of vigilance for the for plant pathologists helping Arkansas soy growers control a potentially devastating fungus.
Asian soybean rust, which can cut yields, has been spotted in four counties: Ashley, Chicot, Drew and Desha, about two weeks after the remnants of Hurricane Fay blew into Arkansas. Fortunately, the disease was occurring at a 1 percent incidence rate.
Asian soybean rust won't be a problem for a majority of Arkansas' 3.2-million-acre soybean crop because it's arriving so late in the state, said Scott Monfort, assistant professor and extension plant pathologist with the University of Arkansas Division of Agriculture. In 2007, the crop was worth $984 million.
"Unfortunately, we estimate that we still have about 200,000 acres that could be impacted by soybean rust if cloudy and rainy conditions persist over the next two weeks," he said.
The remains of Hurricane Gustav brought winds, water and cloud cover to the state last week, and the National Hurricane Center's five-day cone for Hurricane Ike indicates more storm leftovers next week.
With the conditions being right for rust, Monfort and other plant disease experts are combing up to 30 fields a day to gauge its spread and make recommendations for control.
"Three-hundred to 400 miles a day is nothing for those in the scouting group," Monfort said Wednesday. "We're going to continue to scout, and look at the weather patterns and put out another recommendation based on the patterns - as a friendly reminder."
Monfort his colleagues planned to spend time in the lab Wednesday.
"We're going through a bunch of samples today," he said. "We've got samples from 27 counties, everywhere we've got soybeans."
Monfort said Division of Agriculture personnel scouted last Friday for the disease in the southeast part of the state "because we figured it had been two weeks after Hurricane Fay swept through panhandle of Florida, where most of the disease problem is, carried spores over to Louisiana and turned up into Arkansas.
"We figured we'd see symptoms of the disease in Arkansas about 14 days after the storm, and it's just about right," he said.
"We barely got nicked by the hurricane, but it's enough," Monfort said. He said it's likely the disease will be found in one or two more counties in south Arkansas. "We're looking hard for more rust," he said.
It's likely that Hurricane Gustav, which hit the state last week, blew in some disease spores from Louisiana, but the disease problem there was nowhere near as serious as it was in Florida's panhandle, according to Monfort.
"Gustav will make the weather perfect for disease development," Monfort said. The disease prefers prolonged cloudy, rainy conditions, which promotes development and spread.
Monfort urged farmers across the state, including southeast Arkansas, not to automatically spray fungicides for the disease.
Check growth stage first, he recommended. If the crop is beyond the R6 development stage, a fungicide isn't warranted, he said. "Quite a bit of acreage down there is R6 or more, which means beans in the top four nodes of the plant are touching in the pods.
"All three producer fields where the disease was found had very low levels of active soybean rust with an estimated 1 out of 100 leaves showing symptoms, and the disease was developing slowly," he said.
The Soybean Rust Hotline is continually updated with information about the latest rust finds that number is (866) 641-1847. If farmers have questions or concerns, they should contact Monfort at (870) 659-0648, Jeremy Ross at (501) 944-0621, or Amy Carroll at (870) 258-2509.
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http://www.uaex.edu/news/september2008/0912soybeanrust.htm
Contact: Lamar James, (501) 671-2187, ljames@uaex.edu
