Soybean Stop Rust News, KS 05-21-07 IA officials find no more soybean rust evidence; feds investigate origin of infected leaf DES MOINES -- How and why a single leaf infected with Asian soybean rust was found in Iowa in March are questions that continue to be addressed by federal investigators. Officials with the Iowa Department of Agriculture and Land Stewardship and Iowa State University have found no further evidence of Asian soybean rust in the field where the leaf was reported to have come or in neighboring fields. "We did verify that one leaf submitted in a plant sample was infected with Asian soybean rust, but how it got into Iowa still needs to be determined," said Bill Northey, Iowa Secretary of Agriculture. "After careful examination of the materials collected to date, we believe no Asian soybean rust infection occurred during the 2006 growing season in Iowa." After analyzing additional plant materials and finding no evidence of rust, IDALS and ISU officials determined that it warranted further investigation by the USDA's Office of Inspector General. "We take the discovery of any new plant pathogen very seriously, especially one that would be the first recorded occurrence in Iowa," said Northey. On March 8, a sample was submitted to ISU's Plant Disease Clinic. The sample was made up of soybean seeds and plant debris pieces of pods, stems and a leaf. The sample was reported to have been taken from a bin of soybeans harvested in Mahaska County in 2006. ISU's testing revealed infection by Asian soybean rust. On March 12, the USDA confirmed that the single leaf in the sample was infected with the disease. On March 13, personnel from the Iowa Department of Agriculture and Land Stewardship and Iowa State University collected additional samples of seed and plant materials from bins at the location where the sample was allegedly collected. They analyzed the samples and found no symptoms or signs of Asian soybean rust. IDALS and ISU personnel extensively collected remnants of leaves from the field where the submitted sample reportedly was harvested, as well as from adjacent fields. Although many leaves had symptoms of a common soybean foliar disease called frogeye leaf spot, the officials none found had symptoms or signs of Asian soybean rust.
IDALS contacted the USDA's Office of Inspector General, which now is leading the investigation into the origin of the infected leaf submitted to ISU. In March, when the infected leaf was discovered, the Iowa Soybean Rust Team which includes representatives of IDALS, ISU, the Iowa Soybean Association and the USDA Animal and Plant Health Inspection Service pointed out that it did not pose a risk for the 2007 growing season. The fungus and spores that cause the disease cannot survive an Iowa winter, plus they require green leaf tissue to sustain themselves. As in previous years, producers need to continue to be vigilant and monitor conditions that favor rust. They should consult with ISU Extension specialists on identification and management plans and work with the Iowa Soybean Rust Team's First Detectors to positively identify any suspected soybean rust in their fields. First Detectors are more than 600 agribusiness professionals around Iowa who were recruited and trained by the Iowa Soybean Rust Team. They can examine leaf samples and decide whether they warrant further analysis by ISU extension personnel or faculty scientists to detect possible infection. Growers are encouraged to consult with Iowa Soybean Rust Team First Detectors if they suspect plants might have soybean ...