Iowa Corn Crops Threatened by Southern Rust Disease, Potential Yield Impact
A destructive fungal disease known as southern rust has been identified in corn crops across four Iowa counties: Benton, Mahaska, Muscatine, and Louisa. According to Iowa State University Extension and Outreach, the disease was confirmed on July 21 and is currently present at low severity levels. Southern rust, caused by the fungus Puccinia polysora, thrives in high heat and humidity and can lead to premature plant death if not managed, significantly affecting crop yields. Last year, Iowa experienced a severe outbreak of southern rust, resulting in an estimated 7.5% yield loss. The disease typically migrates to Iowa from southern states, requiring sufficient leaf moisture to establish. This year, lower dew points have reduced leaf wetness, potentially limiting the disease's spread compared to 2025. 
