Yellowing "leaf" on my Dendrobium...

[Tetra73]

Any idea why only this particular leaf is having this yellow discoloration and with the brown patch? As I remember, the brown patch wasn't spreading 7 days ago when I got the plant.


nybg_ by vracing, on Flickr

Also, being new to dendrobium, I am not sure where are the new leaves would be growing from since the tip of canes (have 4 in total but only 3 of them look like the one in picture) appears to be some sorts of dead plant matter??? I am expecting the new leaf would overlap the previous one. One of the matured canes does not have this little light brown tip. In fact, new leaves are growing from it overlapping.


nybg__1 by vracing, on Flickr