Black spots on Dendrobium spectabile leaves and cane

[avisignis36@gmail.com]

Help! My den spectabile seems to have a bacterial or fungal infection. It has numerous black spots on the leaves. It seems like they have increased in number (but not size) over the past few weeks. None of the leaves have turned yellow or brown or wilted, and the roots seem to be continuing to grow well. Most concerning I think is the black depressed ring around the youngest cane. What should I do - do I need to cut away all areas that seem diseased?