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The information presented on this page was originally released on May 5, 2005. It may not be outdated, but please search our site for more current information. If you plan to quote or reference this information in a publication, please check with the Extension specialist or author before proceeding.
Sentinel plots ready to sound rust alarm
MISSISSIPPI STATE -- Twenty-three sentinel plots circle the state, standing watch for the anticipated reappearance of soybean rust in Mississippi.
Soybean rust is a devastating fungal disease spread by spores. It can be carried by wind for hundreds of miles, transported on people or machinery, or spread by infected plant material. Left untreated, it completely defoliates and often kills a plant, reducing yields by as much as 80 percent. It was identified in the state Nov. 17, and already has been spotted this year in Florida and Georgia.
Alan Blaine, soybean specialist with the Mississippi State University Extension Service, said the state is monitoring 23 sentinel plots for the first appearance of the disease. The Soybean Promotion Board is funding these plots and their regular monitoring.
"On April 29, we finished our fifth intensive survey of the state. We're looking at our sentinel plots, volunteer soybean plants we've identified throughout the state, kudzu since it's a host and is beginning to green up, and winter legumes such as clover," Blaine said.
Starting the second week of May, the once-weekly surveys will be increased to twice a week. The surveyors travel about 1,400 miles each time without leaving the state.
"Last year, rust arrived too late to damage much of the crop. We may not be as fortunate as we were last year with the timing, but if we find it, we're going to have a two- to three-week jump on handling it for the bulk of the crop," Blaine said.
Nineteen of the plots were planted ultra-early, between Feb. 18 and March 18. The other four were planted by mid-April. All are doing well, with about half of the ultra-early fields blooming, which appears to be the beginning of the crop's most susceptible stage of development.
According to the Mississippi Agricultural Industry Council, each location was planted with maturity group III, early IV, late IV and early V varieties. The plots were planted along the Mississippi Gulf Coast, up the Mississippi River, and in north and northeast Mississippi. Blaine said experts predict light problems with rust this year, based on the disease's historical action when it invaded other soybean-producing countries. When its arrival this year is confirmed in Mississippi, Blaine said a formal announcement will be made and specific action recommended.
"What option we recommend producers follow will be based on how prevalent rust is, where we're finding it, if weather conditions at the time are conducive to the disease's rapid development and the stage of growth of the crop," Blaine said.
Several fungicides are labeled for use on soybeans, and other products are in the process of being approved for use on rust. Availability of control products likely will determine the choices many producers make, as Blaine said chemical companies have not had enough time to get the massive supply of chemicals ready that may be needed one day to fight the disease.
Alan Henn, Extension plant pathologist, said soybeans will not be the only crop affected when rust arrives in the state. Home gardeners should look for rust on their black-eyed or Southern peas, English peas and other garden beans.
"Variety testing in a controlled laboratory situation indicates that we're going to have some problems with alternative hosts for rust, but it's not certain to what degree the problems will occur," Henn said.
He encouraged gardeners who suspect rust to rub the underside of the affected leaf with a white tissue. If the tissue comes away rusty brown, the disease is rust. Take a sample to the county Extension office to be lab tested. The Extension office also will be able to provide treatment advice.
"Gardeners can help reduce the chances of a rust outbreak by not watering with overhead irrigation if they can use drip or soaker hoses," Henn said. "This will keep the leaves drier, especially at night, keeping the plant healthier and limiting its susceptibility to rust."
Joe McGilberry, Extension Service director, said county Extension staff will be valuable resources in the battle against rust, and will be sources of reliable service and information.
"All county Extension staff are being educated about soybean rust and methods of control," McGilberry said. "County Extension staff will play an important role in the battle against rust, taking the lead in their respective counties as we work together to be of significant service to the people of the state."
More information on soybean rust is available online at http://www.soyrust.org. Specific information for Mississippi is linked from this site. Among the educational resources offered are control guides for producers and a ranking of the effectiveness of various fungicides that can be used to combat rust.