night blooming ceres
I live in San Diego Ca and I have a half dozen ceres. This year several of them have developed bright red leaves and look dehydrated. But I do water every few weeks. We did have a light frost a few weeks ago. Is that what might have caused the red leaves. Looks pretty unsightly actually. Other plants around these two show none of this discoloration. I don't normally get frost but I do live on a canyon. Also all plants are in full sun in winter as the crepe myrtle tree they are near is bare of leaves.
Fungal attacks are extremely difficult to stop. The best option is to find any uninfected stems and re-start a new plant from them and throw the rest of the plant away. Fungicides are available that could slow down the fungus attack, but the fungus rarely is eliminated in this way.