DES MOINES, Iowa -- An announcement that a fungus called Asian soybean rust had been found in southern Iowa earlier this year made farmers worry that the destructive growth could damage their fields. But they were relievd Tuesday when officials said the single leaf infested with the destructive fungus must have been brought into the state from outside, perhaps to make people think it had grown in Iowa. The investigation has been turned over to the federal government.
"It's bizarre," said Greg Tylka, a plant pathologist with Iowa State University's extension service. "I can't understand the motivation or a mechanism of how it would be done."
Asian soybean rust is a fungus that can sweep through fields, infecting plants and drastically cutting yields.
The discovery of soybean rust in Iowa, which usually leads the nation in soybean production, would be terrible news for farmers and would force them to buy costly chemicals to ward off the fungus.
The U.S. Department of Agriculture's Office of the Inspector General declined to name the person who submitted the sample. It reportedly came from Mahaska County in March.
Iowa Secretary of Agriculture Bill Northey said the sample was submitted to Iowa State's Plant Disease Clinic and the USDA confirmed it tested positive for Asian soybean rust.
Officials with the state agency traveled to Mahaska County and examined the bin and the fields the leaf reportedly came from, as well as surrounding fields. They found no evidence of rust.
"If it was represented to come from a field that it did not come from, then it's doubtful that it was a mistake," Northey said.
How the leaf got into Iowa still needs to be determined. If someone was trying to blame soybean rust for low yields in hopes of getting government compensation, the attempt was misguided, Northey said. The government does not reimburse farmers for damage by the fungus.
Soybean plants in the same field the sample reportedly came from were suffering from another common soybean leaf disease called frogeye leaf spot, officials said.
Tylka said he doubted that a leaf infected with Asian soybean rust could have blown hundreds of miles into Iowa from the southern United States, where farmers have fought the fungus for years.
He said it was also unlikely it could have been caught in a seed bag or truck, then transported to Iowa and singled out for a sample. The timing was also suspect, he said, because no one would expect to find soybean rust in a bin in March.
"When you add up the odds of all these things happening, it just becomes too hard to believe," he said.
Wright said officials were told the leaf, which was mostly intact, came from a bin that would have held materials that had been thrust around in a combine. "When we saw the condition of the leaf, it immediately put up some red flags," he said.
Soybean farmers in Iowa apparently had their own suspicions and kept cool about the discovery, and Wright knew of no one rushing out to purchase fungicides to apply to their fields.
He cautioned, however, that Asian soybean rust is a real threat to the state, and he hopes the recent incident does not make farmers complacent.
"All it would take is the right field, the right environmental conditions, and we could have an epidemic," he said. "The message to farmers is that this incident is unfortunate, but that they should remain vigilant."