What's eating my Dendrobiums?

[Acharn]

I've got two dendrobiums that are being attacked by something I haven't been able to identify. It doesn't look quite like any of the pictures I've found, although it seemed to resemble cerospora a bit. Or maybe septoria? Can anybody tell? I'm thinking I just need to throw this pair out and buy some new ones. They haven't bloomed in a year, but they've had this condition for a few months now.

[shadytrake]

Originally Posted by Acharn

I've got two dendrobiums that are being attacked by something I haven't been able to identify. It doesn't look quite like any of the pictures I've found, although it seemed to resemble cerospora a bit. Or maybe septoria? Can anybody tell? I'm thinking I just need to throw this pair out and buy some new ones. They haven't bloomed in a year, but they've had this condition for a few months now.

That is called the "Thai Crud" and it looks like you also have bacterial brown spot. I got a small case of both in my GH this spring and they are buggers.

Thai Crud is highly contagious. I would throw out this one and then treat all of your orchids with a systemic and a topical fungicide. Mancozeb, Daconil, Banrot, Cleary's 3336

http://staugorchidsociety.org/PDF/Alert-ThaiCrud.pdf

Orchid Diseases

If you are desperate to keep, use sterile tools to cut all the infected leaves from the plant (in an area away from your other orchids so the spores don't drop). Clean the area with 10% bleach solution. Segregate the plant from others.

[Acharn]

Thanks a lot for the info. "Thai crud" seems appropriate, because I'm in Thailand. Well, for fungicide I'll have to see if my nephew can help me out. He and his wife run a small nursery operation, although in general they don't sell orchids. I know his wife at least is knowledgeable about growing orchids. I always hate to throw out a plant, but these two haven't bloomed in a year anyway.