Getting worried about my sweet corn

Sunburn (  ), damage where they've been knocked, could be a number of things.

Overall though, they look quite healthy and as long as the growing centre is, I wouldn't worry. I'd hardly give them a second look if they were mine.

The soil looks a bit wet to me.  Make sure they are not getting drenched by the rain.  But if they are not outside being hardened off yet don't over water them.

They don't like too much wetness.  I do think Dave is right about sun burn though.