It looks like sun scorch and wind burn. Did you transplant them rather than direct seed them? If so did you harden them off well first? If not then some of it is transplant shock.

If that is all -and the new growth looks ok - they will survive as they adjust but you'll lose some of the older leaves.

But avoid over-watering them or you'll get root rot.

Dave

Thanks for the reply. I direct seeded these. It has been really hot here though (as in many places this year). Temps have been in the mid to high 80's so perhaps that has something to do with it?

I'm probably guilty of overwatering with my drip system so I will cut that back a bit. Thanks for the help.

Keep up with the water. Evenly moist is the goal.

How long do you run the soaker? and how often?

You won't know if you're applying enough water unless you dig down with a trowel to make certain you're running the soaker long enough.

And rig temporary shade for the plants.

I just realized what the white background was. That adds lots of heat & reflected light which rapidly dries out the the plants. Their limited root systems can't keep up with the tops' demands.

As suggested above, rig shade.