Weird marks on Brassia leaf
 

When I went home 10 days for the holidays I left my orchids in the care of a friend. Being gone for such a short time, I was quite surprised to see a leaf on the Brassia in such poor shape. The damage looks very much like spidermite damage, but there's not an insect in sight, and it's the only affected leaf. And now the leaf is starting to roll itself up at the top, I guess it's drying out.

It's not from the sun, the windowsill it was on faces north. I thought it might have been cold damage from touching the glass (had to cut off some leaves on my Max tenuifolia), but my friend said that it wasn't touching.

Other than disease, the only thing I can think of is that since the windowsill is over a radiator, maybe the leaf was sticking out over the warm dry air that was coming up and started to fry. Is the damage consistent with that, or is it something else?

Looks a bit like thrips damage but but as they are biger then mites you would have seen them. I'd say cold or heat damage.

I had an onc that developed something similar on its leaves. It had the similar yellow speckling/pitting, and I never found any spider mites even though people said it was spider mite damage.

http://i2.photobucket.com/albums/y17...9/leafspot.jpg

http://i2.photobucket.com/albums/y17...89/oncleaf.jpg

I never figured out what it was. The plant died, because it had severe root rot when I bought it, but I doubt the root rot had anything to do with the leaves.

Your plant looks healthy, so if these strange leaf marks don't spread, don't worry too much. :)

perhaps it was touching a cold window....

Camille, treat it against mites! :) Once ago someone at the recommended that to another member with a a similar problem. She said it was "Phalaenopsis mites"!! I was very surprised to that comments as I had never heard oh such a thing before! However, it worked the sick plant...

Recently, I have bought the book "Understanding Orchids by William Cullina", and I read again about Phalaenopsis mites (a type of false spider mites)

I've never heard of them before, here is an interesting link for them:
phalaenopsis mite - Tenuipalpus pacificus Baker
Joann

Thanks, I think I'll bring a piece of leaf to work tomorrow and have a look at it under a microscope, and keep the plant separated from the others. But wouldn't other leaves (and other orchids) be affected as well? It's just the one leaf, only on the top side of it and appeared in less than 2 weeks!

If it is mites, I can't do anything about it until saturday, since the shops close at 6, and I finish work at 6 usually... Until then, if I don't see any mites I'll ask one of my scientist friends upstairs in phytopathology (who is an orchidaholic too) what he thinks about it.

Ok, now I'm starting to get worried. The pitting is progressing further down the leaf, and now I've noticed that my Max tenuifolia is starting to show the same symptoms. I'm in doubt as to whether it's mites or not since the damage starts at the leaf tip and works it's way down. The leaves being thinner than the Brassia's the damage is less noticeable, so it may have been there last week already.

I only have insecticides on hand, looks like I need to get something for diseases asap! (unless you still think it's mites) I'm also worried because I have 5 new orchids on the way right now, and I don't want to them catch whatever it is! :(

I'm so sorry to hear about your problems.. :(
I too was gone over Christmas and came back to a sick plant. Its so hard to know what really went wrong when someone else has been taking care of the plant. Hope yours recovers.

What's the situation now Camille? I really don't know what to advise I'm afraid, but it's worrying that you've got this problem spreading.