Southern corn rust was confirmed Friday afternoon, June 9, 2023, on R5 corn in Calhoun County, Florida, which is south of Marianna, Florida
Comments from Bob Kemerait, Extension Pathologist. Warmer and humid conditions will be favorable for spread. As of now, corn at or beyond tassel in extreme Southwest Georgia is most at risk. That includes Seminole, Decatur, Grady, and Early Counties.
Southern Corn Rust is nearly right on time…..we typically find it by the first week in June. Conditions for the next week will be perfect for spread- warm, humid storms. I DO NOT believe in spraying fungicides for “recreational purposes” only. Spraying for the sake of spraying without due cause is a waste of time and of money. However, I DO have tremendous respect for southern corn rust and the damage it can cause if the crop is not protected. Therefore, corn growers in extreme SW Georgia (Seminole, Decatur, Early. Miller, Grady) are encouraged to apply a fungicide (mixed mode of action) to protect their corn crop. Can I guarantee that this will result in more profit? I can’t guarantee much of anything, but I can say that based on my experience and our data, it is a good investment.
Question: “Bob, are you SURE that southern rust is not in Georgia?” No, I am not, and I wouldn’t be surprised if it is. But we haven’t found it yet.
Question: “Bob, where is southern corn rust (and soybean rust) most likely?” Both are most likely in SW Georgia but could be anywhere in the deep south of the state.
Question: “Bob, what should we be telling growers now?” The weather over this week (warm, humid, scattered storms) is near-perfect for the spread of fungal diseases. Much of our corn crop is increasingly susceptible (entering reproductive growth stages), AS IS our peanut crop. Growers are strongly encouraged to be TIMELY in their fungicide programs now for peanuts. The weather is here. Much of the crop is at (or beyond) 30 days after planting, and it gets tough to put the leaf spot genies back in their bottles once they escape.
Recommended corn fungicides can be found here.
The 2023 UGA Extension Corn Production Guide can be found here.