Had to do surgery on a very old mammillaria that had rot on two of its stems. I think the rest of the plant is Ok going to let it dry out and replant it.
Its really wet in the picture now because I washed off all the old soil. It looks like the middle of the stem died and pups were growing in a ring around the old dead center stem. probably how the rot took hold.
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I really wonder, what happened. The root system - at least part of it - looks OK to me. Of the three stems, the one on the left, with the two flower buds looks the best, including the root part. The one on the far right does need to rest on its side for a week or two, until the visible cut has formed a protective skin, During the time out of the pot, it would be a good idea to keep a close watch on the three stems. There is a chance, that the bacterial or fungal infection was able to invade one or more of them. Good luck and I hope, that you can keep your plant alive and growing for a few more years.
Could be a embedded seed capsule under the spines way down low grew a fungus ? I cleaned one out awhile back on the bad stem using hydrogen peroxide and tweezers so maybe that's it? It looked OK after cleaning but left a nasty gouge. Or just dead wood were the main stem had once been started rotting with too much water and humidity? Old clumps are tough.
its M. herrerea a old plant that had a rat eat the top way back in the 1990's and that caused it to clump. Be fun to keep it going after all its been through. It's flowering now on the remaining stems. I'm not going to pollinate it and risk getting seed capsules stuck in under the spines in case that was the problem. Give it a rest it's given me many seeds over the years.
Well, I would not worry about your plant producing fruits. Some members of the plant family Cactaceae hold onto their seed bearing structures for a long time, while others tend to drop them once the seed is mature. If a fruit is removed prematurely, then the danger of leaving an open wound on the plant, which could allow entry to pathogenic microorganisms, is of course higher, than if the plant were to drop its fruit by itself.
Over time the plant will produce a callus layer, sealing the wound and making it difficult for bacteria or fungi to penetrate.
The main thing to do, after a cactus has received a wound, is to keep the wound clean and dry, until the plant has had time to repair the damage.
However, that is not always easy to accomplish, because in addition to being present in or on soil, bacteria and fungal spores may also be moved around by air currents. Most fungi do best, if the moisture level in the air and on the host plant is high.
Hi Harald, I let the cactus dry out, used roottone powder on the lower part of the plant and then repotted it in dry compost. Planted it high in the soil which is 2/3 pumice 1/3 soil and held it in place with gravel around the stems. Should be Ok I think I caught it in time. But you never know.
The remaining stems are flowering that's good. I'll water it lightly in a few weeks weather permitting. Its usually not too dry were I live not like the desert so fungus is always a problem to watch out for. This particular cactus has to be watered with care it will hold water under the spines which act like sponges wicking water up from wet compost then turning the spines yellow permanently.
I put a stone in place of the missing stems so it doesn't look so hacked up .
