Black lines on my Phalaenopsis

[Marian]

Hi everybody,

I have 4 Phalaenopsis and this morning, while I was checking them I noticed that two of them may have problems.

1) one has black lines under one of the leaves and I also noticed that two of the leaves are becoming yellow (as you can see in the pictures)

2) another one has relief white dots.

What do you think they are? What can I do about them? I hope it is nothing serious.

Thank you,
Marian