colourful spots on leaves - viral infection?
 

Please, help me to identify problem with my Dendrobium purpureum. As You can see in the pictures below, there are necrotic (black spots) and colorful shaped zones on its leaves. Is this a viral, fungal or bacterial infection?
Attachment 22945
Attachment 22946
Thanks

I'm thinking bacterial, like a rot of some sort.

I agree with Ross. It looks like something bacterial, but that means you should cut off the infected parts using a clean blade for each cut and then put something (a light bleach solution or listerine or a bactericide) on the cuts and perhaps rub the same over the rest of the leaf surfaces or spray a solution on the whole plant.

I think is bacterial... You should cut them off.... inmediatelly...

Thank you for your comments and advices. I cut all the branches, that were affected by this unidentified bacterium strain, (I want to believe it's not a virus), and sterilized wounds.. I hope my orchid will survive such a drastic pruning procedure... ;)

Is it possible that the plant was in a cold draft or got cold drips of water from above?

hello,

hmmm.... there is such a possibility...
But we can't say for sure, because we got this plant from Roellke (Germany) just two weeks ago and it already had some brown spots on leafs. The weather during transportation was quite cool and humidity high. I thought it was damaged mechanically during transportation, but then those spots started to spread and color around them changed to yellow and red..

I would vote for a bacterial etiology given the pictures and history. Agree with above recommendations of treatment. Treatment of the remaining cut ends with Cinnamon (listerine or physan also works well...) is also a good idea. Good luck!

Cold water droplets may get that king of thing started but would pick one of the other post for treatment at this point. My heater went out on a cold night recently and a few of my Phals look like that - sure didnt make me happy.