Southern corn rust confirmed in Appling county. It wasn’t spread wide across the field, and so little was on the leaf that I nearly missed it (not like the picture below). Nonetheless, it is here. If corn is between VT stage and R6 stage with good yield potential, consider applying a fungicide. Corn sprayed within the past 3 weeks should be ok (unless rain came too quickly after application). Corn is vulnerable to rust if has not reached hard dough stage, and/or if it has been more than 3 weeks since a fungicide has been applied.
If corn is within two weeks (50 percent starch line) of physiological maturity (black layer) it’s unlikely that a fungicide will provide an economic benefit.
Triazole fungicides (like tebuconazole) are effective against rust and have a two week protective window, but lack the broader activity against northern corn leaf blight. Strobilurin products and combination strobilurin/triazole or strobilurin/SDHI have 3 week protective intervals and also a broader spectrum of activity.
https://corn.ipmpipe.org/southerncornrust/ – for an up-to-date map on where southern corn rust has been confirmed.