Diseased leaves on my dendrobium and paphiopdedilum
 

This dendrobium hybrid is one of my favorite ( red violet petal and white sepals with dark red lip). It stayed quiet during the winter, but started a new growth in the spring. The new growth developed lots and lots of roots and a few healthy looking leaves.

Then about three weeks ago, the leaves started to show these ring spots. The rings start out very faint yellowish brown. Over the course of just one day, those rings would turn dark brown with a yellow halo around them.
I trimmed off three leaves in fear of them spreading further. Now the little poor new growth has only two leaves left, one of which has four rings. Two of these are a few days old and located towards the tip of the leaf and look dry with no halo around them. I found two more yesterday. I haven't cut this leaf yet. I have no idea what to do because cutting this leaf would leave the plant with only one leaf that is just emerging from the center.

Next one is a complex type paph with dark spotted flower. One leaf on the new fan started showing red brown spots toward the tip. I left it alone and over the course of one week or so, the spotted area merged to one big brown area. I cut the tip and about one inch further in. That was a couple of days ago and I don't see any more showing up. hopefully that was just nothing. By the way, the picture shows the initial phase with the brown area on one half of the leaf tip. When I had to cut the tip off, the brown area was much bigger.

I'm really concerned about my little dendrobium though.
I read somewhere that these ring spots would not go away usually and that's the end of the plant. :(
Also, I'm not sure if it's worth keeping because I have many other dens right aronud this one and spreading would be even more painful and sad.

Did you do a virus test on the den?
Joann

No, but maybe I should. I read somewhere that the virused dendrobiums sometimes show these ring spots.
Then I would just toss it.
I mean it's been frustrating enough cutting youn tender leaf with ring spots thinking and hoping all is well, then you find more ring spots on newer leaf and cut that leaf off....goes on and on.

I'm sure the plant is not getting enough food with three leaves gone already.

Spreading that quickly it sounds like a bacterial infection... Other than cutting off infected leaves, have you treated it with anything? Physan might help.

I thought about treating it with physan as well because my first guess was also bacterial.
With the halo around the spots. Thing is the ring appears very faint and just over the course of one day, it becomes very dark with the definite halo around it.
Now this poor little leaf has four ring spots.
Another interesting thing is that the size of the rings do not grow but only numbers do.
Once the ring spots get a few days old, the halo around it disappears and look dry. Maybe the mode of bacterial infection for this specific type or the plant cells are killing some of themselves around the infected area to block the spread. no idea really. just a speculation.

Maybe I should treat it like tomorrow.

On the first, what bothers me is the symetry, I find this very strange. Now it looks more like bacteria/fungus than virus.

The second I wonder. But maybe an insect passed by, as some zone are collapsed and green. The brown could something propagated by the bite.

I don't have the head clear enough to go eventually further, but I'd cut the leaves, add cinnamon and think about some general treatment as something fishy is around.