gopher? something toxic was poured out in that place? min

The only thing I can think of is clogged emitters. A picture would be helpful.

I agree with emmarene, maybe your sprinklers aren't doing what you think they are.
Is there a block wall, tree or other plant blocking the sun?
Maybe there is a big rock underneath roots. I have dug up so many at least 4x4x4 inches around here.

Tree root competition is something else to consider.

Try not to disturb the Chondropetalum root system. They don't like that. You can try giving them some deep soakings. They come from areas of seasonal flooding that alternate with drought.

Thanks everyone for the suggestions.