what happened my Dendrobium ?
 

Dendrobium Alliance help me what that black dots on the leaf....what can I do for thıs my friends?

I'll bump this as I think I've got the same problem, black specks all over just one of the leaves on the lead cane, they feel bumpy to the touch, but if I try to scrape them off it damages the leaf. Any ideas?

Sun damage perhaps? Is it in strong direct light? This is the time of year that the light intensity is changing. I really am not a good one to give ideas as dendrobiums are not easy for me to figure out, either. But I have been moving my chids around alot lately due to the season change.

Could be fungal, if it's just on the leaves. Also, the underside of the leaves are looking silver, which could be spider mites. Wipe the leaves off with a damp, white paper towel and if you see a rusty residue, you may have red spider mites. I would treat with a fungicide and also something for mites. Fungal problems usually don't kill the plants, but mites will. They also spread disease and are usually a problem in the fall and winter when the humidity drops. Good air movement decreases both problems.

Likely fungal but could possibly be viral. One of my dends had similar spots which later developed into a ring shaped pattern that was obviously an ORSV infection. I would separate it from the rest of your collection and observe for a few months.