We have had a lot of rain this winter in Southern CA. My beautiful organ pipe cactus has developed a large split in the outer skin. Will it heal over? Can I save it?
Likely, it will be ok. You might want to treat with a fungicide just in case, though. Keep an eye out for spreading. If it starts to spread, then I would cut that whole arm off and treat that with fungicide, as well.
This article will offer more care information: