Rural signs

[pyesetz]

There are many farms in my township.  Quite a few have these “genetically-modified corn” warning signs, but I didn’t see any of those today.
Here is a sign that I did see today.  It is an advertisement for ProRich seeds.  Considering the ProRich product line, I’m guessing that this field is planted with alfalfa.
Finally, I present to you the signs that moved me to write:
WTF?  Who are these signs for?  People who can read words like “toothpaste” and “ethanol” from a moving vehicle but who don't know what cornstalks look like? I note that this cornfield is across the street from a country grocer that serves many city-slicker tourists (and might be owned by the same family).  This could just be the usual farmer's lament “I bet you city folks probably don't even know what food really looks like, do you?”  Or maybe it was for some school field trip?  For immigrants who’ve never seen corn before?  And why are the signs a stark black and white?

You might notice at the bottom of the nearer sign there seems to be a logo and maybe the manufacturer’s name for this sign, but I didn’t get out of my car to look at it and the photo isn’t clear enough to make out.