Thank you for the reply. Because there are so many possible causes for this, I am going to show a picture that may shed light on my problem.
Double click on the thumbnail. Both of these phylloclades were healthy until 3 or 4 days ago. Even the new growth on the one on the right still looks fairly good. The opuntia seems to be doing fine, as evidenced by the new growth on it. It is trying to grow from some of the areoles. This makes me think the roots are fine. I believe our heat (107 F yesterday), is the primary cause, and gives the fungus Phytophora (VERY bad for schlums), an opening. The fungus Trichoderma is supposed to be attracted to cornmeal, and will attack the Phytophora. If this will work, I would rather do it than use a systemic fungicide.
It would not bother me a bit to use cornmeal on the yard, flower beds, or anything else outdoors. I am wanting to keep my schlums inside, and am worried about the molds this may attract. I don't have one or two pots of the things, I have a room full of them. That means I may have fungus or molds growing that I don't even know about.
Sandih has said the Trichoderma is not harmful. But, a room full of it? And maybe fungus I don't even know about? I have searched online, and there are plenty of fungus out there that I want nothing to do with.
Mixed into the potting soil, is this safe?