What is Southern rust and is it something we should be worried about? Listed is a link from NCSU that may help answer some of your questions regarding rust in corn.
Generally common rust is something we see every year in corn and is not considered to be an economic threat. This year we have both common and southern rust showing up. Southern rust spores were blown in with Hurricane Arthur which was one of the earliest storms on record for our area. Most of the corn in Southeastern NC is in the dent stage and will probably not benefit from a fungicide application at this time. Late planted corn may benefit from a fungicide application if the yield potential is there. A handful of growers that I know protected their crop and the aerial application cost plus fungicide cost was roughly $31 per acre. The risk/reward factor will cost a grower about 8 bushels of corn per acre.
One 1200 acre corn producer from southeastern NC shared with me his thought process. He elected to protect 400 acres of his crop with a preventative treatment. The 400 acres protected was planted in mid-May and has high yield potential. His justification for treatment was that he was not treating the entire crop therefore estimated his risk/reward cost was $10 per acre.
Regardless of how you assess the risk/reward factor southern rust is abundant throughout our entire region. It is not difficult to identify. Active southern rust spores will be orange in color with raised pustules that look like miniature volcanoes. Southern rust spores will be found on the upper surface of the leaf where common rust can be found on both sides of the leaf. Common rust spores are generally red in color.
Learning opportunity
I am working with several producers that decided not to treat and several that decided to treat for southern rust. We will monitor and take pictures weekly to learn as much about this problem as we can. I will share the good, bad and ugly with you as it develops. Yield data will also be collected. If you have questions or need assistance please give me a call.
Sincerely,
Rick Morris
