Spots and rot in Dendrobium

[lexicon]

I have two dendrobiums with these spots on the leaves that tend to spread. I have a ton of air flow in my growing area and physan 20 isn't stopping the spread.

I cut off the offending pseudobulbs at the base with a sterile knife. Is there anything else I can do to stop whatever this is?

The spots themselves are dry and the discoloration of the pseudobulbs is firm.


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[bil]

I use mancozeb. In your shoes I would cut radically and try another fungicide or two.

[lexicon]

I just ordered some Clearys, and I'm spraying with hydrogen peroxide 3% in the mean time. I really hope I can save these two plants.

It's a Den. aberrans and a Den. Micro Chip, both are in spike/bloom.

[silken]

I wouldn't cut the pseudo bulbs off if they aren't black or soft. Maybe the leaves. I get a lot of spots and blotches on my den leaves and I use Cleary's and Physan and never get water on the leaves and have good air movement 24/7. I can never figure out why.

Are you keeping them fairly warm? Mine have to be grown in a greenhouse that is cool in winter, but I do keep them on a heat mat. The nobile's which are kept cooler also seem to get more spots than other people's but I just consider it to be like the Oncidium thing. I can't seem to prevent it and I am not sure it is actually something that is spreading.

[lexicon]

I already trimmed leaves a few months ago, but the spots are spreading to multiple pseudobulbs. I don't want to risk the entire plant by ignoring these spots. I do occasionally get black spots just on the leaves, but those appear one day and do not grow in size or continue to spread to other parts. I assume those spots are heat stress because they usually happen to me in the summer.

[silken]

OK, if they are spreading onto pseudo bulbs, you don't want to risk them spreading further. Mine are usually only on leaves. The warm growing Dens shouldn't be too stressed from heat unless they don't have enough water or protection from direct sun. But maybe if you have too high of humidity and heat, it causes some bacteria or fungus to thrive. Hope you figure it out.

[King_of_orchid_growing:)]

Next time when you post a question, it's best advised to mention specifically what specific species or hybrid of orchid you're referring to. Dendrobium is a very large genus of orchids that encompasses orchids that come from a varied set of environments. It is not fair for people to guess what kinds of Dendrobiums need help and give you advice that could be wrong because they were not well informed as to what it is you're dealing with. It is also not helpful to you as the inquirer to receive information that doesn't apply to your situation or cannot really help you out in a significant or impactful manner. Although from the photo I'm assuming you're dealing with problems with Dendrobiums within the section Latouria.

[Leafmite]

How are you growing this? Are you growing it under lights? You see, what you are showing in these pictures looks quite familiar to me. :|
I have a little experience with these after killing a Microchip and the two 'parents'. I actually replaced the Microchip and, now that I seem to have gotten the culture down, I may go ahead and replace the other two.
Here is what I did wrong:
I grew these directly under my T5HO (four lamp, four foot) lights, didn't water often enough, it was cold at night and there wasn't enough humidity. The lights were pretty close to the plants.
After I killed them all, I mentioned to one of my fellow OS members about the experience and was told to grow them in shade, give them good humidity and to keep them warm. So, this time around, I have the Microchip with my Phal bellina and Phal violacea in a tabletop Ikea greenhouse, right next to the lights but not directly under, sitting on a heat mat. And, this time, the leaves do not look like what you are showing but are perfect. Even better, it initiated spikes and has been in bloom.

[Leafmite]

I hope this helps you.

[lexicon]

Thanks everyone! And my bad, I'll make sure I'm more specific next time.

I think I cut off 15 growths, of which 5 or so had spikes. That's ok, I still have 20+ spikes.

Hopefully keeping this a bit warmer and not as bright will help it along.


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