Dendrobium - leaves turning black

crm8484June 24, 2012

I picked up this Dendrobium 'Elma White' off the clearance rack last year. After a few months leaves started getting yellow and then black ... starting usually at the tip then eventually (fairly quickly) turning completely black (this was a while ago, so not sure of the exact sequence). I switched out the moss substrate that seemed over-compacted and was burying the lower few inches of the stems. It ended up losing all the leaves, but i left it and lo-and-behold, new growth started! However, now one of the new leaves has turned black also and i'm seeing some black spots on another new leaf. Is this a disease or maybe something as simple as overwatering? I've looked at several sites and can't seem to find a description (or photo) that seems to match what i've got going on exactly. Any ideas from the experts out there?

Thanks!

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arthurm(Sydney, NSW AUST)

You have a warm growing hard-cane Dendrobium. I suspect that the correct name is Dendrobium Emma White.

As for culture..... depends on where you are in the USA, but generally it needs warmth, good light, humidity and fairly even watering throughout the year to do well.
Easier in tropical places, Hawaii, Singapore, Miami and so on.

    Bookmark   June 24, 2012 at 3:18PM
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James AKA lumpy_j

Are those white rocks in the mix Dyna Rock or diatomite? If so get rid of them. I used some on a few dendrobiums a few years ago and none of them did well at all in it. Some died the rest took a while to recover.

It looks like its happening from the tip inward so I would guess some kind of burning from fertilize or salt build up. Do you have a water softener? If it is fungal or bacterial dont use anything copper based to treat it.

I don' think moss is the right mix for this plant, the leaf damage could have happened in the bud stage before you noticed it.

    Bookmark   June 24, 2012 at 7:35PM
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crm8484

the rocks are just a few my son was playing with from some "gemstones" we were given that i stuck on top, so shouldn't be contributing anything. haven't fertilized this one at all, so wouldn't be burn or salts. not softened water, so not that either (potentially quite hard water actually, but hasn't seemed to bother other plants we have).

anyone think it's fungal or bacterial? if so, any specific products or family of products?

thanks!

    Bookmark   June 25, 2012 at 8:59PM
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jane__ny(9-10)

I have had that happen to Catts and seem to remember a dend with the same problem. I think its bacterial and would probably recommend an alcohol spritz or a q-tip. It is tough to get rid of and you will probably lose the plant.

Try alcohol on a q-tip, full strength. Just wipe the black area being careful not to get it down into the crown. The leaf should dry up in a few days.

You could try to cut the black area off with a straight edge razor and then wiping the cut edge with alcohol. I worry about spreading it further into the plant when cutting while the infection is active.

You have nothing to lose, try the alcohol wipe first. Keep the plant in an open area with good air circulation. Don't overwater.

Good luck,
Jane

    Bookmark   June 25, 2012 at 11:01PM
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richardol(Santa Royale CA)

I think the problem is that water got into the new growth and it didn't have time to dry before night. That can kill new growth.

Rocks are a good medium for hard cane Dendrobiums. However, plants often don't like a change in medium. The few rocks on the top of the bark aren't enough to worry about.

    Bookmark   June 28, 2012 at 9:26AM
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