What can help save my moon cactus? It is turning yellow dry and brittle. Roots look good as far as I know. What is wrong? It may have got a frost bite in our window since the weather has turned cold.
Certified GKH Gardening Expert
At this point, the bottom half may not recover. It has been uprooted on top of what appears to be a fungal infection. The top of the cactus is a separate type of cactus grafted on top. This has a chance for a little longer if you pull them off and sow them in their own pot or pots. They will not live very long, though as they don't produce their own chlorophyll. That is why they are grafted on top of the green cactus.
Infections like this are commonly caused by over-watering. These are very drought tolerant, and like the soil to remain on the dry side.
Here is an article for more information on their care: https://www.gardeningknowhow.com/houseplants/devils-backbone/devils-backbone-plant.htm