Cactus - cork or rot?
I just divided a pot of cactus that had a few mature pups. The purpose of the divide was to investigate why the cactus were turning brown. Some of the pups had turned 80% brown. I expected to find rotting at the roots - but there is no rot smell nor mushy brown roots. The brown parts are not quite as firm as the green parts but it isn’t soft either. I plan on repotting all the cactuses but am not sure what to do beforehand? I don’t like the brown look - is there anything I can do about it? When repotting, should I cut off the base of the bigger one despite the healthy roots? Do I treat the ones with roots different than the one’s without?
It looks like your cactus was damaged by a root/crown rot, probably caused by a Fusarium or Pythium. Unfortunately, there is not anything we can recommend that would be curative for these diseases and symptoms. We recommend disposal/replacement of the plants.