My Queen of Night is dying, how can I save it? Please help!

I am very new to gardening. My plant got some kind of disease suddenly. The leaves turn yellow at first and now the whole plant is infected. Is it possible to save it and how? Please help. I really like this plant and I don't think I can get another one if it dies. Should I cut all the infected leaves ? Will the disease spread to other plants? I have a few orchids too.

 

I am not convinced that it is a disease yet, it doesn't look like anything I have seen. Unless it is a virus, they sometimes attack Epiphyllum (your plant is an Epiphyllum oxypetalum).
Could it be too much direct sun? This species prefers diffused light.

 

It was indoor before and the leaves is turning yellow. I thought it needs sunlight so I move it outdoor last week. I hope you are right! I will move it away from the sun right away and hopefully I haven't done too much damage to it. Thank you for your advice. Is there a way I can tell whether it is a virus attack? Should I move my other plants away from this plant?

 

Sunlight is good, but nearly all cacti - including most of the "desert cacti" - need an acclimatization period of gradually increasing exposure before they can tolerate the ultraviolet light, very much like (fair-skinned) humans. This one, which is an epiphyte and normally grows in at least partial shade of other vegetation, is even more sensitive (I have "experimented" with one myself ...). It should do better for example under a tree or behind a transparent sheet of something capable of spreading out the light over a bigger surface.
I have never seen a virus infection in my plants, viruses in cacti seems more common in wild plants, but my impression is that they spread more slowly than this. And if the plant has been behind glass until a week ago it is pretty clear that this is sunburn. So no, I would not have isolated it, just moved it to a more shaded spot. Fortunately this species grows very fast. :)

 

Thank you for your explanation. Just one more question, is it better to leave it as is to recover or should I remove one or two really bad one and wait for new leaves to come out?

 

The damaged tissue will not recover and seriously affected parts can be removed now, but if you wait a while scar tissue will form, and it will become more apparent what parts are worth saving.

 

Hi Mary,
just wondering where you bought your plant from? Appreciate your help!

 

Hi Emmy:
I didn't purchase the plant. I was really lucky to get a clipping from my friend's friend so I am not sure where you can buy one.
Sorry I can't give you any help.

 

It can often be found on auction sites etc. as they are very easy to propagate.

 

Wow...Thank you for your reply though!

I will try that, thank you!