Damaged Moon Cactus

[Brunoordino]

Hello everyone, so I'm kinda new to collecting cactuses so I don't know much yet.

My moon cactus looks like it's dying.It has a violet color and is grafted to another cactus. It's bottom part is appparently rotting. I'd like to post pics but it says file too large. It's one of my first cactuses so I'd really like to save it. If I can, can someone teach me how?

[Brunoordino]

Shown below is my cactus. Please gelp, I feel attached to it since it's one of the cactuses that made me love planting.

[hegar]

I just answered a few questions presented by fellow blog member chiari, who has an almost identical problem with the same kind of plant you do experience, i.e. a Gymnocalycium sp. cactus grafted on a Hylocereus sp. rootstock.
First I cannot tell, if the "Moon Cactus" is dying or not. These plants cannot survive without the Hylocereus rootstock, because they do not produce chlorophyll. So they derive their nutrients and growth from the rootstock plant, which is able to photosynthesize.
I also noted, that your plant has a very similar looking lesion at almost the exact spot (near the graft union) as the one shown by chiari. I wonder, if these two plants were not perhaps grafted at the same nursery.
Now to the condition of your Gymnocalycium graft. Except for the lesion, I do not see anything wrong with it. Are you sure, that the grafted cactus top is really rotting? If the lesion is not increasing in size, no additional lesions are formed, and the cactus does have the same softness or hardness throughout, then things should be OK. If there is a rot, the cactus will quickly become very soft, with the whole center turning to mush.
There would not be much that I could suggest you can do, because oftentimes the rot has already spread throughout the plant. With a larger cactus you may do some "surgery" and remove the infected part plus about an inch or more of the seemingly healthy part. Then the leftover cactus could either be grafted once more, or - if it can survive on its own roots - be planted again, once a callus layer has formed at the cut end.
As stated above, your cactus can only survive, if the rootstock remains alive.

Harald

[Brunoordino]

Hi Herald! Thank you so much. After inspection I think it will be fine. I tried touching it annd felt now "soft spots". Also, I took a few pics of this cactus 2 weeks ago and no new spots were discovered. Your knowledge greatly reassured me. Thanks!

[Shane]

Actually, Brunoordino's Gymnocalycium does have chlorophyll. Although lighter colored (red, yellow, etc.) varieties lack chlorophyll, the dark ones do have it, enough even to be healthy without grafting

http://hoorayplants.blogspot.com/2013/1 ... n-its.html

Is an example of this

[hegar]

Shane, you are correct. If the grafted plant is actually a Gymnocalycium mihanovichii var. friedrichii, the death of the rootstock would not mean the most likely end of the cactus on top. Those are usually being sold "on their own roots".
There would not be a good reason, to graft them onto a Hylocereus rootstock, except perhaps to make them grow faster. The yellow, orange, red versions of this cactus cannot survive without the green companion plant onto which they are grafted.

Harald