Dendrobium Phalaenopsis: Brown Rot or Sun Damage?

[modifiedskittle]

I'm new here and looking for advice on my new dendrobium phalaenopsis (at least that is my best guess... I got it home and realized it had no label ). I just bought this orchid 4 days ago (Saturday) from a nursery. This morning I noticed that the top leaf has turned a brown/greyish color and the next lower leaf has a spot that is doing the same. At first I thought it may be sunburn because there are no blinds/curtain on that window, but the sun doesn't get too bright there. Then I looked at the picture I took on Saturday and noticed that the leaf was starting to brown at that time so it leads me to believe it started while at the nursery. All the leaves are also water stained/spotted so I'm guessing the nursery let it sit wet. Upon further research I think it may be brown rot. The first two pictures are from this morning and the third is from the day I got it. If you zoom in you can see the top of the leaf is brownish. It is a very tall orchid and I haven't examined the roots. It is packed very tightly and I'm not sure what the medium is. I was going to wait to repot until it was done blooming. Is there anyone that can help me identify what is wrong with this orchid?? I just don't want to take the wrong steps in correcting it.

As a side note: what is the best method for cleaning the water spots off the orchid leaves?

[Roberta]

Looks like sunburn to me. That could even happen on the way home - sun blasting through the car windows (and it can happen in a few minutes or even less) . There's nothing to do and no long term harm... those burned leaves will drop, there are plenty that look fine. Let it bloom, then repotting will be a good idea... plants tend to bloom best just before the outgrow the pot (they like "tight shoes) and nobody pays the grower to repot so most newly acquired plants need it. As long as the weather is warm, timing not critical. Personally, I don't clean leaves... spots don't bother me. But if they bother you, a good "cleaner" is milk diluted 50:50 with water. Use a tissue or cotton swab depending on the size of the area you want to clean.

[modifiedskittle]

That actually makes sense now that you mention leaving it in the car!! It took a while for me to get it home after I got it (maybe 2-3 hours) and I'm in Texas where temps are 100 degrees during the day. I didn't even think about that!! I went ahead and cut those leaves off, but I'm glad to hear that it is probably just sun burn as opposed to some infection or disease.

I'm still torn as to whether I should repot it now or after it is done blooming. I want to wait, but from what I can tell it is packed tightly in peat moss (and maybe spagnum moss underneath) or something similar and I don't think that's good for the orchid.

[Roberta]

You can safely wait on repotting, but it probably won't bother the flowers if you do decide to go for it. This is a time of rapid growth, which is ideal time to repot. Just be gentle with roots - don't try to clean off all the old medium, just shake and wash off what comes easily and leave whatever sticks.