Southern Corn Rust is a fungal disease caused by the fungus Puccinia Polysora. Southern Corn Rust is DIFFERENT than regular corn rust. You can identify Southern Corn Rust by the orange to tan pustules that occur in clusters on the upper leaf surfaces. When you walk through a field of corn with rust pustules the orangish color will transfer onto your skin and clothes. The rust attaches itself to the plant and can significantly impact yield if the case becomes severe. It uses the nutrients in the plant to grow and reproduce. The rust pustules cause tears in the leaf epidermal tissue; this impedes the plant’s ability to regulate water efficiently. This will eventually reduce grain fill. Wind currents spread the disease, and it thrives in high relative humidity and temperatures of around 80 degrees Fahrenheit. Once the rust spores enter a cornfield, it takes roughly two weeks for them to develop into pustulates if conditions are favorable.
Many different fungicides can be applied to corn to prevent and treat Southern Corn Rust. Field corn should be protected using a fungicide spray through the “dent” stage, according to Dr. Bob Kemerait (UGA Plant Pathologist.) Most fungicide labels say “Do not apply within 30 days of harvest (30-day PHI) for forage, grain, or stover.” – https://www.syngenta-us.com/current-label/quilt_xcel Farmers can decide which approach they want to take. As of July 16, 2024, Burke County has one positive ID for SCR. Burke County Extension Agents Peyton Sapp and Cliff Collins, along with summer intern Devan Godbee, have been taking corn samples around the county. THERE IS NO NEED TO TREAT, IF YOUR CORN IS BEYOND THE DENT STAGE. If you are interested in looking at a map of Southern Corn Rust within the state you can visit the Corn ipmPIPE website at https://corn.ipmpipe.org/. As always, if you have any questions please do not hesitate to call our office.