Corn Southern Rust Threat Still Low

by Paul Vincelli, Extension Plant Pathologist, University of Kentucky

Southern corn rust was discovered quite early this season in the deep South. It has since spread to Arkansas and Georgia.  See http://scr.ipmpipe.org/cgi-bin/sbr/public.cgi to monitor its progress. 

The risk of the disease currently seems low, for several reasons:

·        Western Kentucky is experiencing extreme drought.  Furthermore, air masses over the region have been dry, reducing the duration and intensity of leaf wetness periods due to dew.

·        Corn crops are generally past silking, and yields are expected to be low in many areas, because of reduced pollination.  Even if southern rust should move in later, it might be hard to recover the cost of a fungicide in a field with low yield potential, especially if air masses remain dry and disease progress is slowed.

I think the situation still bears monitoring, but I am much less concerned about this threat than I was a month ago.