To me, that plants looks like it has been ignored in hot arid condition for so long that there was no moisture in the soil. No plant will ever die like that from too much water.

I read somewhere that peas can suffer from root rot from too much water and I thought that maybe I was watering them too much - once a day, in the evening. Maybe I need to water them more than just in the evening.

Snap peas are a cool weather crop. They will not grow in hot weather. Here in zone 8, I can grow them, by planting in midwinter for spring harvest or some times in late summer (September) for fall harvest. Fall plantings are iffy here. In zone 10 I woukld expect that you need to grow in a winter garden.

That explains everything. Thank you, "farmerdill." I will grow them in the winter. There is also rain then.