Corn fungicides added around tasseling time have done an excellent job in curbing southern corn rust in Illinois.

 “If we see southern rust moving up to Illinois around the Fourth of July, that is when we begin getting concerned about it,” says Carl Bradley, University of Illinois (U of I) Extension plant pathologist. “In 2009, it showed up early and caused yield losses at Dixon Springs (where the U of I has a testing site) in southeastern Illinois.

The good news? Applying a fungicide at tasseling or R1 (silking) does an excellent job of protecting corn from southern rust. A 2010 U of I trial showed a field treated with fungicide yielded 220 bushels per acre, dwarfing yields of an untreated field by 40 bushels per acre.

There’s a new tool you can use to project the progress of southern corn rust at www.ipmpipe.org, after which you go to the southern corn rust portion. This Web site can help you ready a fungicide if disease is imminent.