Pay special attention to the driest parts of the field. 

Usually the disease appears as olive-green mold. The moldy growth appears powdery and is due to the massive numbers of spores produced by the fungus. The spores are dispersed easily in the air, and they may appear as dust when the husk is pulled back. 

The mold is commonly found at the tip of the ear, but it may be found anywhere on the ear, especially where physical injury occurs to the kernels. 

Other ear molds of corn are caused by fungi that produce various powdery molds, including green molds. Penicillium kernel rot can be quite common on injured kernels, but that tends towards a blue-green color than olive-green. Trichoderma ear rot is more greenish than olive green.

What should you do if you suspect a case of Aspergillus ear rot? We can confirm the causal fungus in the UK diagnostic labs, which may be useful in deciding whether to test for aflatoxins. But please bag the sample and inform the lab that it is a suspect case of Aspergillus ear rot, so that the staff can protect themselves by handling the sample in a biosafety cabinet.

UK doesn’t offer a routine testing service for aflatoxin, but there are numerous other laboratories that are equipped to analyze corn samples. A list of laboratories is available at http://www.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/PPFS-MISC-1.pdf

This is an incomplete list; other competent labs exist, but this will serve as a handy reference for some of the available laboratories.

This is a really important point: If you properly collect 10 samples from a moving stream of grain, aflatoxin quantity will vary quite a bit among those 10 samples. That is the nature of sampling for a chemical present at parts-per-billion levels. 

This variability will be even worse if you have submitted ears collected while scouting. Just be aware of this.

As far as what the grower does with the information from the scouting, I don’t have specific recommendations to offer.  ID-59 will provide some helpful ideas, but ultimately, we in Extension provide the education, and producers will make their decision that fits their marketing plans and risk-management philosophy.