hard to say. I would have said slightly dehydrated, but the leaves do not look droopy. I'm guessing it's just sun scald from being planted in full sun and with large space between plants. Peas prefer semi-shade in my experience as it keeps them a little cooler once june hits. But i have my pea breeding patch in nearly full sun this year, but i have mine all planted very close together so they may in effect help shade each other. Again hard to say or give advice. The picture on the bottom looks like it's just hit it's time and is dying like peas usually do, but the top photo does not look that way. Sorry can't be more help. Perhaps someone else will chime in.

This happened to my pea plants too last year. I found out they were receiving too much sun, so this year I planted them in containers so I can move them into the shade. It seems to be working.

I would have to agree with Keen101 and say it may be sun scald. Are your plants in direct sunlight? For how many hours?