Christmas Cactus (Zygot?) Dropping Foliage
The fleshy sections (leaflets?) lose their crispness (go limp) and fall off. I have not been able to detect any insects. There are some blight like spots on some plants but not usually on the dropped plant parts.
Should I just throw out the plants and start over again? I have had these plants for many years. I tried repotting them, but this did not seem to make a difference. I did put them outdoors for a couple of months. I recently repotted a couple of them, pruned them back and have brought them back into the house. I will need to decide what to do with the remaining plants as a killing frost will probably happen within the next couple of weeks.
Note: the only new plant in the house was an orchid plant back in May. . . could the problem be related to that plant?
Usually the symptoms you describe are associated with root malfunction i.e. the leaves are not getting moisture therefore they are getting soft and falling off. But you say you've had them for several years, and repotting didn't help. Do you test the soil moisture in the bottom of the pot before watering? It should be nearly dry before adding more moisture. Has the light changed? Maybe a tree has grown or there are new curtains, something that cut the light recently. Definitely don't give up on them yet. Try moving them around, or changing the watering a little. The blight like spots are a puzzle; are you seeing the woody sort of appearance that old christmas cactus stems take on? I don't see how the orchid could be at fault, if you see no bugs on any of the plants. Bugs are not invisible, believe me.