I'm going to assume you direct seeded the corn, correct? Do you have a picture of what you think might be mildew? It might be nothing, but at this point, if they are soft, I'd replace them. Prolly not much of a chance for germination at this point

Actually, I did not directly sow them. I decided to play it safe and start everything in artificial conditions just because of the strange weather we've been having in central California for a while now.

I can try to get a picture and perhaps post it after this, but for now I can at least give a better description:

The "mildew" is a very light color, maybe white. It looks like incredibly fine little hairs just growing off of the seed. It runs off of the surface of the seed quite easily, I didn't even have to scrape it at all. Also, I don't know if this would even make a difference either way, but nothing else seems abnormal. Nothing strange on these four seeds that didn't go on the others, no foul odor to suggest that it may be rotting, etc.

I'll try to get a photo though and post it. In the meantime, I'll go ahead and plant four more seeds to replace these just to be safe. I can give the plants away or something if these four surprise me. However, will it most likely be as I said, where these four replacements will always be a little behind the others in terms of maturity, or might they "catch up" at some point?

When is your last frost date? Corn does MUCH better directly sown than transplanted.

I've seen the image you describe on some of my seeds, but what it exactly is escapes me right now. Maybe someone else can chime in.

I'll wait for your picture! ;-)

Wait a minute. You planted 10 seeds? What good are they going to be? You can't grow 10 cornstalks and get anything.

I believe that some do plant seeds like that in Earth Boxes or whatever they are.