A couple sickly cacti
I have two different species of cacti that aren't doing very well, and maybe you can help me identify and fix the issue.
The first is one of my fence post cacti. It was growing slower than the other, and started developing a black spot near the crown. The spot quickly grew to a blotch and spread horizontally across the near-top section of the crown. It's crispy and "sucked-in" now, but the blotch has slowed its spreading.
Could it be sunburn? It is in a partially shaded area outside, but it's also been about 110 for a couple weeks. I moved it to a more shaded area.
I'm not sure of the ID of the other cactus but It looks like a spiny version of a lophophora. I have a group of three in one pot in a mostly shaded area outside, and they were looking shriveled despite watering them frequently. I finally just sat the pot in some water for an hour, and two of them perked right up. Maybe the soil's got too much drainage? The third hasn't perked up at all and continues to wither. I tried soaking the pot again and it didn't seem to help, and I don't want to endanger the other two healthy cacti.