The saga continues

[pickmary]

Hello there,

So I have had my orchids for almost half a year now! So far so good, I am getting new spikes on all of them so I must be getting the hang of this! I have one concern with my dendrobium however. One of the canes has tuned yellow in the middle. It's just a small cane, and the rest seem fine, just wanted to check with the pros here to see if I should be concerned. Here is a picture. Thanks!