Is this normal? Dead circles on cucumber leaves.

At first it was just one or two...now there are several leaves with this brownish/dead discoloration. Should I be worried?

Here's another pic...I think you can see the brown spots a little better in this one.

I wonder if that could be just a little sunscald on the leaves, but I'm not sure. The first thing is to check the underside of the leaves very carefully for aphids, etc. Aphids can be discouraged by a strong spray from the hose to knock them off, but you might need to spray for other pests. Are those spots brown, or are they more yellowish as they appear in the photo?

They're more brown, like brittle dead leaves in fall...but only in those patches.

I'm really confused about the sun and sunlight when it comes to plants. I thought direct sunlight meant out in the sun with no shade. Whenever I see tomatoes, peppers, cotton, squash, cukes, etc...growing on large farms, they're always just out in a field with no trees or anything. And it's hot as h-e-double-hockey-sticks out there. The air literally ripples with heat around noon.

So why is it that my plants are suffering sun damage (which I believe you are correct and they are)?

Do you water your plants from above? Those spots look like places where water droplets might have concentrated the mid-day sun, acting like little magnifying lenses to fry the leaf beneath.

Sometimes I'll see sun scald on plants that are newly set out, or on leaves that have been disturbed so that they are now getting more sun exposure (happens easily with cuke vines that I have to "encourage" to stay in the garden rather than growning out across the lawn).

As for the fields of sun-worshipping plants, I think if you looked closely you might see some of the same thing... we just pay more attention to individual plants in our smaller gardens or containers.

Oh -- and you did check under the leaves, right? :-)

Yeah, check under the leaves. I saw no aphids, though there are some really tiny black ants that seem to have made a home there. Not a lot of them really...I'll only see about 5 or 6 out at a time. I haven't really taken a step to eradicate them as I have a soft spot for black ants. Living in the South, we're pretty much all at mercy to the invasive fire ants (I think every Southerner has a nightmare story about being attacked at one point in their lives)...so whenever I see some harmless varieties I live and let live.

I have watered during the day, so that might explain the scalding. Also, we've been experiencing some heavy morning fog and light morning showers. Not so bad except that the sun then comes out and steams everything until well done. If it weren't for the cicadas and spanish moss, I'd move up North in a heartbeat. ;-)