Does anyone have any suggestions about what I can do to save my cactus?

I've summarized a timeline below

3-4 weeks ago: Small sunburn-ish looking thing appears. It's near the top of the cactus, not near the base at all. No watering.
2 weeks ago: Begins to expand downwards and cause some shrinkage. No watering.
1 week ago: Continues expanding downwards and now a bit to the sides as well. No watering.
3 days ago: I repot the cactus as the old container is really quite terrible and also take the chance to investigate whether there's any root rot.

  • Findings / Actions:
    • Soil is really dry
    • No foul smell from the roots / soil
    • Doesn't seem to be much in the way of roots at all, really
    • Clear off whatever old soil comes off easily, leave the rest, repot. Place in area that gets afternoon sun.
    • No watering.

4 days ago: Image 1 No watering.
Today: Image 2 and Image 3. The shrinkage has not actually reached the base yet, but the yellowing has been steadily expanding. No watering.

If anyone has any suggestions that'd be great. If anyone knows what I did wrong I'd be very open to hearing that too; I'm taking care of two more plants and really don't want to make the same mistake again.

Thank you very much in advance, and thanks also for making it to this point of this wall of text as well heh.

Image 1 Image 1 Image 2 enter image description here Image 3 enter image description here

1 Answer 1


It looks like bacterial rot or a fungal rot infection. Because it has advanced and is so close to the crown of the cactus, it is doubtful that the plant can be saved. You can try to cut away the infected region with a sharp blade, so that perhaps one of the dormant "thorn clusters" might sprout into another growth. The link below may be of further help.


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