Will neem oil work on black spots on orchids?

It sounds like moisture is the most common problem with black spots on the leaves. I found an article on orchid problems that includes the black spots. I hope it helps you with the problem and that it hasn't gone too far. Good luck, I hate when I have problems with all my orchids!

https://www.gardeningknowhow.com/ornamental/flowers/orchids/treating-orchid-diseases.htm

Neem oil mostly kills insects and does not repair spots on plants. Good luck!

Hi Laurie,

Destroy an orchid if you see wet, dark spots on the leaves and pseudobulbs, as they usually indicate a bacterial or fungal disease, such as black rot or brown spot. Because these diseases are difficult or impossible to cure and spread easily from one orchid to the next, it's safest to get rid of the orchid immediately.

I have had this orchid for 16 years and have had black spots before.