Can anybody tell me what this flakey tan coloured crust is on my cacti? It starts at the bottom and goes up, peals fairly easily but comes back. I've lost some but others have survived for years with it. I don't think I'm over watering and they are dry from Oct- late April early May. I try to water from below so water doesn't stay too long around the plant. Any suggestions oh how (if possible) to get rid of it and prevent it would help too.
