By SCOTT NILES Courier staff writer
April 05, 2007 11:52 pm
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OTTUMWA — Spores of the Asian Soybean Rust have been found in Iowa for the past two years, but only one case of the actual disease has been spotted.
A noticeable case of the crop disease was discovered on a soybean crop in storage last winter, but it was killed off with the cold weather.
Mark Carlton, a field specialist with Iowa State University Extension, said the rust needs certain conditions in order to develop and survive. It is partial to warmer, moist temperatures, found in most southern states. The spores that have been found in Iowa were never fully developed into the disease because the weather was not ideal.
“We have only seen that one case of the actual disease in Iowa so far, but it can come at any time,” Carlton said. “If it were to arrive in Iowa, in say, June or July, we could have a serious problem.”
David Wright, director of contract research for the Iowa Soybean Association, said if the disease were to spawn itself on a host, it could wipe out 80 percent of a farmer’s crop yield if left untreated.
“Farmers should not panic; there are fungicides that can be applied to eliminate or minimize the amount of loss,” he said.
Wright said the disease is capable of traveling to Iowa at any point throughout the season depending on weather patterns, but is not anticipated.
However, he and Carlton said farmers should keep an active eye on their crops this year to make sure there are no noticeable signs of the disease anywhere, along with other soybean crop diseases that can be just as harmful.
“They should be checking their fields for the other deadly crop diseases such as frogeye leaf spot and sudden death syndrome, anyhow,” Wright said.
Another prevalent disease among Iowa soybean crops for the past several years has been soybean cyst nematode. This infection can be just as harmful to the crop yield if left undetected.
Despite the common soybean diseases, rust is harder to notice and more timely to treat once it is spotted.
“Soybean rust spores are not noticeable just by looking at the plant,” Wright said. “Farmers probably won’t notice rust until it has developed into the disease.”
At that time, farmers have roughly two days before it starts spreading to other parts of the field at a rapid rate.
Carlton said Iowa farmers have been lucky the past couple of years avoiding the rust, but that does not mean it will not strike the Hawkeye state.
As a form of protection and “early warning,” he said there are sentinel plots set up in most of the Midwest and some of the southern states to detect the arrival of such diseases before they arrive.
“These are fields that are checked daily throughout the growing season for diseases,” Carlton said. “There is always someone checking them. They act as a warning system to the areas to alert farmers of any diseases.”
However, Wright said there are patterns known as “green bridging effects” where the disease skips and entire area.
“We have seen instances where a wind-blown disease is in Arkansas and Iowa an nowhere between,” he said.
Though detection is something that officials are working to increase, Carlton said farmers are encouraged to check their fields periodically and alert their county extension office if they notice any disease.
“From there, the county extension office can alert other farmers and let them know that a disease has been found,” he said.
Scott Niles can be reached at (641) 683-5360 or via e-mail at sjniles@mchsi.com.
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