Dendrobium phal losing leaves - help!!

[Klup]

I’ve had this orchid for a couple years, and while it’s never bloomed it has had healthy looking canes and leaves (the oldest canes are leafless). I just noticed that all the leaves on one cane (not the most recent, but the next to last to appear) had significant yellowing and they fell off when barely touched. The canes are all firm and no rotting that I can see. I took it out of the medium and while some of the interior roots are mushy, most feel firm and healthy. I’m thinking of treating with physan 20 and repotting, any other suggestions? It’s my only phal type dendrobium, according to the seller it’s D. Burana jade x emaron gold. I keep it in a shaded west facing window where my dendrobium nobiles have grown well. Thanks!!

[estación seca]

What are your temperatures? This is a warm growing class of plants that drops leaves when they get too cold. Unpotting a Dendrobium in the wrong season can produce a serious setback. The time to repot is when new roots are just beginning.