Black spots on yellowing leaves

[mrs.TF]

Hello people
I bought a den. Dawn Maree from the Toronto Orchid Show this last saturday..
I've potted her in sphagnum moss (the vendors had them with bare roots), all fine until 2 days ago until I have seen leaves yellowing, and with these ugly sunken spots..
It was on another room, so nothing went further, but..what is this? And showing up so rapidly?
I know dens shed leaves in winter, I know they react to change of medium, location, etc..but still..
Any ideas?
Thanks a lot.

[Connie Star]

I'd guess it's a fungal infection, but, despite all my posts, I am a beginner.

[BobInBonita]

Like Connie said - we're all beginners here - no matter how much experience we have we keep learning from each others responses. Everybody is right from their own perspective, but their (or my) perspective might not be applicable to your situation. Since I can't see the plant, these are guesses that might point you in a direction, but only guesses.

My first suspicion is that the orchid is too wet - sphagnum can really hold a lot of water, but it is obviously a guess since I don't know your watering habits.

Not all dends drop their leaves in winter - it really depends on the variety, so this could be normal or this could be a major issue.

Did the leaf yellow and then develop the black spots, or did the leaf have black spots first? If a leaf dies normally it will frequently turn yellow, and before it dries out fungus can set in. That seems less problematic than when the fungus starts on a healthy leaf and then the leaf dies.

Not knowing the condition of your dendrobium when you bought it, it may have been dormant and dry because of the bare root. I've always felt that overwatering a dormant plant can be more serious than overwatering an actively growing plant.

[Pasque]

Maybe a reaction to the cold? I've seen this on mine before when they were hit with cold air. But I'm not 100% with that.

Did you wrap it before going outside? Leave it in the car?

[johnblagg]

Could you post a picture of the entire plant ?That might help a bit more .....

Were these leaves nice and green when you got it?and went yellow fast?It could be they were simply ready to drop anyways but untill we have a bit more to go on its hard to say....It would also help if you could tell us what kind of Den it is.OOPS just reread the post and see the name ......sorry

I have had leaves that were ready to drop yellow quickly ...

[johnblagg]

I did little google serching and it appeares to be a dendrobium of the negro-hirsute type I dont know if that means it may be a decidious type or not but they say it flowers directly off the canes also.

[mrs.TF]

Thanks very much for your replies..
-after buying it from the To show, I had it on my car, there was heat, and it took me at most one hour to reach home..
-at home, I have washed the roots, then I have put it on sphagnum, but the pot is a net one, from a strawberry basket..it dried out fast..
-when I potted it, leaves were good, green and glossy
-now, i have written to the vendor, and very nice of him, he responded me..
He told me that I should not worry, because it is stress related..change of location, medium, conditions etc..
I will try not to worry
I did not know that they develop these spots when stressed out, I had a couple of them shedding leaves..
I guess time will tell..
I will put some cinnamon on the leaves nevertheless, just to be on the safe side
I will let you know how this goes..
Thanks very much, everybody