Wanted ASAP: Advice for halting sudden, virulent bacteria or fungus on Dendrobium

[bethmarie]

This Den Hibiki looked fine a couple of days ago when I bought it. Below are pics of what I found tonight.

I'm so hoping there's a night owl on who can identify whether this is bacterial or fungal and what the best, most aggressive treatment will be. Whatever this is, it's fast, and I'd really like to stop it before it progresses much further.
In case the last pic isn't clear, it's the underside of an affected leaf.

I'm off to do some research myself!
Thanks for any and all suggestions that don't involve napalm

[bethmarie]

After researching, I'm still uncertain what this is.

The plant affected is a Dendrobium, so that means no copper, correct?

[Orchid Whisperer]

I think it's bacterial, similar to Erwinia. The affected leaves seem to be "on their way out", I would cut those leaves off entirely, using as really sharp blade (like a single - edge razor blade). Flame sterilize & cool the blade between cuts (to prevent disease transmission.

When you are done cutting, put the plant somewhere where it is isolated and you can keep it under observation and DRY. Withhold water until you are sure it is not spreading further.

Some Dendrobiums do lose their leaves seasonally. I don't know if yours is one of those. Some orchid leaves seem more disease-prone as the leaf ages and prepares to drop off.

[Ray]

Soak the plant overnight in a 2% Inocucor Garden Solution. I saved a phalaenopsis with erwinia that way.

[bethmarie]

Thanks for the fast feedback. I am pretty anxious to take the best action for this.

OW: You are correct that the affected leaves are on their way out. They separated from the canes with little resistance. Hibiki does lose its leaves on mature canes eventually. Most of the diseased leaves were still young, though.

Ray: I don't have Inocucor on hand. Wish I did.

Thanks to both of you for weighing in so fast.

[Ray]

Originally Posted by bethmarie

Ray: I don't have Inocucor on hand. Wish I did.

So order it. I can ship tomorrow, so you ought to get it Tuesday or Wednesday.

[dounoharm]

no copper on dens?? my dens are subjected to the Spanish inquisition along with the rest of the heathes...ie, copper twice a year.....and, when I really feel like it, I empty the whole bench, and photon the heck out of bench wall and probably me up to the elbows....but I got over those silly dens that require special care...give me a phal type den and I am happy!!

[Leafmite]

Until you get what Ray is offering, Isopropyl alcohol can help to dry and disinfect. I have saved orchids using it but I used cotton balls and a new one for each leaf. Spraying it would probably be easier. Just don't get the alcohol on the roots. I applied it twice a day.

I have known people in the past whose Dendrobiums all died when they accidentally used a Copper-based fungicide so it is possible that newer varieties are not as affected as in the past or, perhaps, there is some other factor in play. I have no idea. It isn't just Dendrobiums that are affected by copper...air plants and some other plants are also not cool with it. I have found with my plants that some can be pretty finicky about certain chemicals.

[Ray]

...and it is not ALL dendrobiums that are damaged by copper-based chemicals.

[PaphioAdict]

I am curious how such a disease gets started in the first place. Are we watering in the evening? Is the potting media stale as in more then two years old?

---------- Post added at 11:33 AM ---------- Previous post was at 11:31 AM ----------

Originally Posted by Ray

...and it is not ALL dendrobiums that are damaged by copper-based chemicals.

Good too know Ray. I was sincerely wondering since I have one of these little creature in my house and strangely it's blooming!