(Atlantic) – The 2025 Pro Farmer Crop Tour found mixed results across the Midwest, but much of the concern centers on the spread of southern rust, a fast-moving fungal disease now confirmed in 17 states.
Iowa State Extension Agronomist Aaron Saeugling says it’s the worst outbreak he’s seen in his two decades on the job. He explains the challenge is twofold: the incubation period is extremely short, and the spores that cause the disease are carried long distances by the wind, making southern rust a non-yearly concern. This year, spores moved in with spring and early summer weather.
Saeugling says yield losses will depend on several factors, including how early the infection reached a field, whether fungicides were applied, and the corn’s genetics. “It really comes down to a field-by-field basis,” he said, adding that the disease creates multiple challenges for producers.
While it’s too early to say how southern rust will ultimately affect harvest, Saeugling noted there is still a strong corn crop across much of the state.
Southern rust, caused by the fungus Puccinia polysora, reduces photosynthesis and can cut corn yields by 30 percent or more under severe pressure.
