What is wrong with my Dendrobium( white thing on the leaves). Please help me...

[danliz]

Hi everyone,
I am new to orchid so all of the orchids that I have are having problem, and I don't know how to solve it. I tried to research but still don't get it.

I bought this Dendrobium one more month is a year now. At first, I put it them in the house because it was blooming so pretty. After blooming and grew one new stem (which have one leave cut) at the same time, I put it outside and decided to re-pot it. I didn't know what kind of pot or mix so I put it in a huge pot with a lot of charcoal and covered on top with moss. The leaves of new stem grew longer than normal, and the stem never grew new leaf. At the same time, some white thing appeared (as you can see in the photo) on both side of the leaves. The leaves are dull/rough/drooping), and another new stem grew. But the orchid seem not healthy, so I decided to re-pot it. The root system was rotten, and very little new roots grew. I cut off one of the old stem that you can see in the picture (the one has only two leaves) because its root was all rotten. It actually had no root at all, but I gave it a try by still potting it in another pot (again the pot was huge too). I placed the another half which had two new stems and one old stem in its huge old pot. After a while, white thing was everywhere on both Den. orchids, and they showed no grow so I re-potted them again. This time they are still with alot of charcoal on the bottom and moss on top, but they are placed in a smaller pots (as you can see on the pictures). The stem that had no root showed two new tinny roots, and the other showed a few new roots. But I think I am gonna repot them again using at a lot tree fern and moss and bit of charcoal. What do you think?

So that is the history of this Dendrobium (now become two Dendrobium),

So my questions are:

Why the leaves grew longer than normal?

why are they so low at growing?

What are the white thing on both side of the leaves and the tree (sun burned? or bug?)?

There are some slightly yellow spots and tiny black spots on the leaves as well. Why?

Should I quarantine them with my other Phal. orchids?

What should I do now?


Thank you so much in advance for your help!!