Asian soybean rust has never been identified in an Iowa field since the disease was reported in the continental United States in November 2004. However, the disease now has been conclusively identified on soybean plant tissue, which was submitted to the Iowa Soybean Rust Team last week.
This soybean residue is reported to have been recovered from a bin of soybeans produced in Iowa in 2006. Efforts are underway to identify other remnant plant residue that may show symptoms and signs of the disease in order to figure out the details of this event.
The fungus and the spores that cause the disease cannot survive without green leaf tissue and will die during Iowa winters. The recently discovered rust fungus does not pose a risk of infection for the 2007-growing season in Iowa.
Doesn't pose risk for Iowa in 2007
"The fast, conclusive identification of soybean rust in this one particular plant residue sample illustrates the rapid diagnostic capabilities available at Iowa State University to protect the state's soybean crop from the threat of this disease," says Wendy Wintersteen, dean of ISU's College of Agriculture.
"This discovery reminds us that it is possible for Iowa fields to become infected with this disease," says David Wright, director of contract research at the Iowa Soybean Association. "Nonetheless, growers should not overreact to this development. Instead, growers must be ready to act appropriately and economically in 2007 should this disease again show up in Iowa and be a threat to soybean yields."
Bill Northey, Iowa Secretary of Agriculture, says the finding does not necessarily increase the risk for the 2007 crop. "The confirmation of this disease in the 2006 crop does not guarantee that we will have Asian soybean rust in the 2007 Iowa soybean crop," he points out.
Don't rush out to buy fungicide - yet
"As in previous years, farmers should monitor the growing conditions and weather conditions that favor the development of rust and consult with ISU Extension specialists on identification and management plans. However, it is imperative for farmers to avoid the inclination to panic and take drastic, costly and unnecessary action before positively identifying soybean rust in their fields."
The Iowa Soybean Rust Team is made up of specialists from ISU's College of Agriculture and ISU Extension, the Iowa Soybean Association, the Iowa Department of Agriculture and Land Stewardship and USDA's Animal and Plant Health Inspection Service. The Iowa Rust Team recruited and trained more than 600 agribusiness professionals from 2004 to 2006 to serve as "First Detectors."
These people can examine leaf samples and decide whether the samples warrant further investigation for possible infection with soybean rust by ISU Extension personnel in the state or by campus-based ISU scientists.
Growers are encouraged to consult with Iowa Soybean Rust Team First Detectors in the 2007-growing season if they observe plants that they suspect might have soybean rust. There is no charge to consult with these First Detectors concerning possible soybean rust infections. The names and contact information for First Detectors is available on the Internet at www.soybeanrust.info and at county Extension offices.