What's going on with my Dens?

[RandomGemini]

Both of my Dendrobiums seem to have this issue with dropping leaves. The plants in question are Dendrobium Micro Chip and Dendrobium Mini Snowflake. Purchased from the same vendor, several months apart. I have tried treating with physan 20 and it does not seem to be having an effect.

Any ideas?

[Leafmite]

I would be concerned about the roots. I kill everything in bark so you must understand that my suggestion will be very biased against bark. :|
Over the years, I have found that the Dendrobiums do very well in basket pots with red lava rock as you can water them like crazy without rotting the roots. I have the aggregatum and the divisions of my Phal-type Den. in red lava rock. My new Microchip is in LECA, my new favorite medium and, yes, a basket pot...for the same reason.
If you use bark, you need a really small pot so that the Dendrobium can be root-bound and drain the moisture quickly from the medium.
Good luck!

[RandomGemini]

I have them potted in a mix of bark, moss, and a bit of hydroton at the bottom of the pots for drainage. I don't water them as much as I should and at first I thought this was because I was watering them weekly. Now I water twice weekly. Fertilize once a week. The roots on the outside of the clear pot on the mini snowflake look good.

The micorchip, the one pictured in the green pot, I just repotted into this 4 inch pot. It had this issue with spots on the leaves and leaves dropping before I repotted. When I went to repot it, the root mass wouldn't fit in a 3 inch pot and this was the next smallest size I had.

[Leafmite]

If the roots are good, what are the other conditions? How long have you had them? Did the orchids look good when you bought them? If not, might someone have used a fungicide with copper on them? (a no-no for Dendrobiums)

[RandomGemini]

The orchids did look good when I bought them. The mini snowflake was just out of bloom and the microchip was in bloom. They are grown indoors. I have had them on my dining room table since they started showing symptoms a month or so after I moved them up to my office. Conditions in the dining room are household normal. Low humidity, temps right now are steady at 68 degrees during the day and household temp drops to no lower than 63 at night. My office is much better. 68 is the low in there and humidity is between 40 and 50%. None of my other plants look like this except these two dens. I've had them right around six months.

[Leafmite]

I really cannot be certain what is happening, then, if the roots are good. I hope mine doesn't suddenly start going downhill. I have only had mine for a month so anything is possible. :|

[wintergirl]

I am trying to rescue a den phal that has been loosing leaves. The owner had re-potted it a month ago, but I went ahead re-potted anyway when she brought it over. The bottom 2 inches of the pot was very moist and breaking down with some white patches on the bark. It had an odor too. The roots didn't look too bad but they were sitting just above this mush. So it is good advice to look at the roots and the entire media. You never know what you can find. She had big air holes that she made all around the bottom of the pot, so you never would have expected what I found. I bleached the pot and put a bunch of styrofoam in the bottom with large fir bark. Hopefully that solves the problem.

[RandomGemini]

I'll pull them from the pots then and take another peek at the roots. Can't hurt to try. I was thinking it might be some sort of disease, because I can't seem to come up with something I might be doing wrong.

[Bulbofett]

The first picture looks fungal to me because of the yellow "halo" around that dark area. I would definitely keep it separate from the rest of your collection with suspicious looking leaves like that.

[NYCorchidman]

Those are bad.
One of my den. microchip has outbreak earlier in the fall. It was a surprise because the plant had been growing so well and looked great.
Then one day, there were these three ugly brown rings with yellow halo.
I always called it dendrobium mystery ring. I have lost a couple den phal that I absolutely loved to this ring disease. I would trim off the affected areas, but only to find them come back. I eventually end up with leafless dead plants.

Back to my den. microchip. I cut the affected area and so far I have not seen the disease and I'm happy!

Physan 20 is not going to work for this. It's just a mild surface cleanser at best in my opinion. It never worked for anything and I threw away the old bottle that was sitting around.