Fungus on Phalaenopsis? Leaf Disease on Dendrobium?

[KristofferNgo]

Hi

I'd like to ask for your help what's wrong with these orchids... first is what I think is a baby Dendrobium. While I was in the process of repotting Phalaenopsis and Dendrobium orchids, I found a baby orchid somewhere and decided to put it in its own pot. I assume it's a Dendrobium orchid because it looks like it has the structure of one. Recently, one of its leaf looks like it is rotting, but I don't recall leaving water on the leaf. Whenever my orchids' leaf is wet from my watering, I make sure to wipe it off. Is this a disease or is the leaf just rotting? The rotting seems to be spreading on the leaf... should I be concerned? Pic is below

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On the second batch of pictures, you'll see white spots on the stem of a Phalaenopsis orchid. It just appared today. I don't know what they are, but I could scratch it off using my nails. Is this a type of fungus? If it is, could you suggest what natural remedies can I use?

Imgur: The magic of the Internet