Each spring many Agronomists are challenged to diagnose varying residual maladies that may or may not affect crops. There are distinctive diagnostics that when observed can tell the story of whether a herbicide has caused damage to the crop. With the recent 2-3 inch of rain and the fact that some growers applied residuals just ahead of this rain we could see some injury to newly emerged plants. Here is a table of some common corn herbicides and what to look for if injury is present.
I might also add that it is one thing to see the injury but there are products that do tend to harm our crops more than others. Dr. Curran rates products from Fair to Excellent pertaining to crop safety. Chances are in adverse conditions some of the products listed as Fair may have a potential to injure your crop. This link if you follow it scroll to the second page to the right hand column for crop safety.
Couple these together and a story could then be told. If you require further restrictions and use recommendations follow this link and read and follow the application restrictions.