Damon Smith, Extension Field Crops Pathologist, University of Wisconsin-Madison
Wisconsin corn continues to remain free of southern rust as of August 10, 2016. However, new confirmations have been reported in southern Indiana (Fig. 1). You should continue to scout the corn crop for southern rust. However, the window of risk is quickly passing for much of Wisconsin. Once corn reaches the milk stage (R3), risk of yield loss from this and other foliar pathogens begins to quickly decline. Thus, as long as corn remains free of southern rust for another week or so, we will be in good shape for the rest of the season. If you need assistance in identifying rust on corn, leaf samples of corn plants can be sent in a sealed plastic bag with NO added moisture to the University of Wisconsin Plant Disease Diagnostic Clinic (PDDC). Information about the clinic and how to send samples can be found by CLICKING HERE.