Identification: Is this a fungal

what is this. it is on a corn cob that i picked from the garden the other day.

 

Yes, a fungal disease, caused by Ustilago maydis.

Seems the fungus is edible when young, and considered a delicacy in Mexico: http://en.wikipedia.org/wiki/Corn_smut

 

I'm envious - I've always wanted to try this, and I'm told fresh huitlacoche is good but that the canned version in mexican food stores is pretty bland.