Dendrobium with faded spots and splotches on leaves
 

Hi, I have an old dendrobium that I badly neglected during the summer, a NOID from Walmart. I let it get really dry a lot during the summer and it stayed outside in sometimes 100 degree heat, mostly 90's, still very bad for it. It got pretty beat up out there. When I brought it in for the winter I still haven't treated if very well. Bad orchid keeper. :(
Here are some things that really concern me about it. The worst thing is the leaves are getting these spots on them, about dime size and usually one in the center. It starts out yellow and then fades to tan and dies. The change in color is not sudden, it gradually fades back to green. I've already lost one leaf this way. I cut it off fearing it was a disease.
Also, the older and younger canes are two different colors, the older a lime green and the younger dark green. The leaves are also mottled with darker and lighter spots. I fear virus. There are also some spots I thought were scale but when I tried to scratch them off with my fingernail I had to dig through the leaf to get them off. Here are some pictures:

Hi, we have the same climate, hot and dry. The temperatures here are even higher in summer (up to 110 degrees). I grow my dens outside, sheltered from the sun, but I water and mist them a lot.
Judging from my own dens, I believe that the spots on the leaves were caused by sunburn, nothing to worry about. They start white, become yellow and finally black necrotic spots. :twocents:
Also the younger canes are lime green and the older are darker. Yours is the other way round? :hmm

What a shame - the mount is beautiful and beside the coloration, the plant is really nice!
I also think it is a sunburn problem. If the new shoots started outside, they are darker as a response to intense light - sort of an orchid tan; I have had them do this in the past. The spots are burns I am afraid. Once a burn occurs, there is nothing you can do to save that part of the leaf.
The mottling may be from needing iron, sort of a chlorotic issue. But it may also be a virus and the stress of high temps and intense light may be enough for it to present. The last photo concerns me the most as you can see the mottling very well and it looks 'patterned' or 'mosaic-like'. May be time to test!
Keep us posted on what you find out!
Steve :waving

not sure what to do...
 

I would've thought sunburn too, but they are on leaves that are shaded by other leaves, and the last one occurred after I brought them in. Also they spread and eventually make the whole leaf yellow. Then again, I don't think the last one has spread so I don't know. I'll go look in a minute. Oh, and it looks like the new cane is lighter because the new cane grew in behind the old one. It throws me off too. How easily do viruses spread? This is my oldest orchid and I really hate to get rid of it, although I guess it would be okay as it was a gift from a previous boyfriend. Current boyfriend has never said anything though. I don't really mind getting rid of it I don't guess. I just don't like the idea of killing it. It's just a crazy idea probably as it's just a NOID from Walmart and probably diseased as well, but does anybody want it?

Oh, could the mottling be cold damage? I have it right against the window trying to separate it.

Oh, and I thought bright light made them lime green? Not really sure how it all works. I know I have some that really throw me off because they turn purple in the sun and I'm really not sure how much light they need.

Sorry to keep posting but I keep coming up with questions. I think I misunderstood you about the color of the older and younger canes. I just thought maybe the plant was moving nitrogen from the old cane to the newer ones and maybe it needs fertilizer? I guess I could just keep it around and try to take better care of it, but I'm worried about viruses.

ambersartain:
I don't know of any virus / fungus / or bacteria that cause purple-shading; usually, from what I have seen in mine, the color is too well dispersed or uniform to look like a disease symptom. If a disease discolors from the inside, it usually is concentrated around the vein area or in blotchy patches throughout. If it is from the outside, it is usually in patches also and can be anywhere, but is more defined in the coloring.
I have just known this to be a reaction to suddenly stronger light. I think if the move into the light were slower and gradual, you would have lighter color green leaves, but, at least in my mind, this is JUST a leaf color, will have no effect on the blooms, and is not an indicator of an ill orc.
Hope this eases your mind.
Steve:waving

Oh, I meant I had some other orchids that are naturally purple shaded when exposed to sun. Not this one. This one is colored just like it is in the picture.

Sorry!
Sort of crossed-threads there for a moment. Thanks for setting me back on track.
Steve:waving

That was funny! You're welcome! :)