Hi. I'm new to the forum and this is my first post and I could use some helpful advice.

About 15 years ago I purchased a rooted cutting of a very large crested cactus that I was told was Pachycereus pringlei, though I do not know the actual species. Due to it's large size, it did not move with me and stayed at my parents house where I only see it every couple months. Long story short, after the recent heavy rains in Southern California, it became water logged and nobody noticed until it rotted from the inside and died. It had a single offset that crashed to the ground but appears mostly healthy.

The pup was about 22 inches long and had some mushy black rot around where it detached from the mother plant. I cut about 3 inches off the bottom until it appeared that no discoloration remained, and using what I had, cleaned it with alcohol and dusted it with strong Hormex rooting powder. I set it aside to callus but less than 24 hours later the wound has since turned brown in spots but appears firm.

Any advice for success is appreciated. This is my prized cactus and I want to do anything I can to save it. Does it look healthy? Should I address it differently or simply leave it alone to callus?

Also, can anyone identify the variety?

I am attaching a couple photos for reference.

Thanks,
Neil

It looks like you could remove the bottom third (cutting where the stem is narrowest) if you think maybe the first cut was too close and the rot has gotten in there. But in all fairness this is going to be an ugly scene no matter what, as the cut surface scars and heals. The rooting powder has to be relatively fresh (not expired) for the active ingredient to work. But even the powder alone (so-called inactive ingredients) probably helps dry things out up front, and worked in your favor that way. Discoloration without softness would be less concerning to me than the other kind.

This is going to take some time, and while the cactus recovers from the cut you need to keep the cut surface dry. Especially in the beginning months after you pot it up. The fastest way to make this end badly is to water early and often. Consider a mix of at least half pumice or even all pumice (substitute sharp gritty rock equivalent if you prefer). Keep this project out of the rain come fall-winter to avoid issues early on.

This is not something I have done, but I would guess it is going to require patience and restraint on your part.

to the forum!

Hello @NeilR25, it will require your utmost patience to steer away from watering and wait for the roots to form. The last time I had something similar happening, I think it took the whole Spring and Summer season to recover, cacti is just so slow growing, and got to use a very gritty mix as mentioned already. It was a learning curve for me too that time and taught me a hard lesson to always make sure media is well draining and containers being used always have drain holes.

Good luck on your plant! It does have good potential, so be very patient as you wait. Try to position them in a bright light/warm spot for now, like a morning sun area.

Thank you. Patience is not my strongest quality but I am doing my best to leave it alone. It is drying under a pergola at the moment and continues to feel pretty firm. I'm thinking (hoping) the discoloration is due to some kind of oxidation. I kept the material I removed from the base that I suspected of having surface rot for observation. Not sure if it is any real indicator but so far, while those slices have also turned brown where I cut them, the surface rot has dried up and the interior tissue remains firm and free from obvious rot (pic below). Perhaps the mother plant successfully kept the rot isolated from the pup. Sick beyond hope of survival, with her dying breath, she cast off her child, her only chance at surviving. Romantic. Tragic.

I plan to rotate it every few days so it does not send roots out the side but I may pot it in a bone dry pumice/coarse sand/cactus mix in a few weeks. Not sure yet. I covered the wound with a sulfur slurry which dried almost immediately into a thin powdery layer that I hope will provide some protection. I'll post updates.