Such a BIG flower, and a very attractive flower, on a little cactus. Hi Alain. Is this M. theresae on its own roots or grafted? Here in the US it's unusual to see one on its own roots. I've grown M. theresae twice and lost it both times from mites. I've also lost M. saboae and its two subspecies goldii and haudeana from mites. Perhaps I tried to grow all of these during a time frame when I had an infestation of mites under my lights. They are all splendid in flower, and the spine clusters up close are wonderful.
The plant is on its own roots. I have heard they are susceptible to red spider. The spines are great but unfortunately I cannot produce a photo.