Dendrobium Aberrans with white dried spots on leaves

[edisonghc]

Just purchased this last week from a local shop. I'm growing it in bright artificial light, temp from mid to high 70s day and night, humidity 50~70, constant airflow from a fan, water when media is dry about every 5 days, 50ppm water not fertilized yet, only a tiny bit of calmag, (.5 ml in a gal) once.

First 3 photos are taking in 3 consecutive days. I applied Physan on Day 2 but that didn’t seem to stop the spread. There is very subtle yellow marks around the dry white spots, more pronounced on the backside.

Any ideas on what may be causing this? Fungi/bacteria? Or light/water related issue? Appreciate any help!

Original posted on: Help identify the cause of leaf white spots on Dendrobium Aberrans : orchids

[edisonghc]

Higher resolution photos:

Day 1:
Imgur: The magic of the Internet

Day 2:
Imgur: The magic of the Internet

Day 3:
Imgur: The magic of the Internet

Backside:
Imgur: The magic of the Internet

Note:
Moss has been removed as suggested by a reddit reply saying dendrobiums don't need moss and it's good to isolate variables.

[blurrycollie]

Hey bumping up this thread.

I too brought a specimen of Den.Aberrans two months ago from a local shop. The fungus issues on the leaves were much worse than yours. My initial environment was too wet for it so I noticed the patches were getting worse. Then I adjusted the misting cadence + fan timing, I also cut away the bad leaves. Now I’m seeing relatively stabilized condition on my existing leaves.

I was thinking whether this is normal for all Aberrans. Since if you look at product photos from Brookside Orchids (where I got mine from), you can even see the spots on the webpage photos.

I see mine consistently sending new roots + a new spike. Maybe this is not so troublesome?

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[estación seca]

Welcome to the Orchid Board. For some reason this didn't show up back in June. Sorry you don't have an answer.

Imgur is saying traffic is too high so I can't see those photos.

Den. aberrans is in the Latouria group. They don't like to dry out at all during the warm growing season, and need just a little less water in winter. It looks to me as though it's been kept too dry. Many people here on OB stand Latourias in bark in shallow dishes of water. I would think every 5 days, under a fan, is not enough water.

They like high humidity. Setting a fan on it will make it dry out even faster. Most homes with central air conditioning or heating have plenty of air circulation. Unless you're growing in a humid greenhouse or terrarium you might not need the fan.

Perhaps it has been too brightly lit. I wonder whether those spots might be burns from heat or excessive light. Your humidity range isn't high enough to promote fungus, so I don't think your plant has fungal issues.

I wouldn't use a fungicide unless you know exactly what you are treating and know the fungus is susceptible to the fungicide you have. Many Dens are highly sensitive to the copper in Physan. It can damage leaves.

It needs regular fertilizer with all nutrients, not just cal/mag, especially if you are using pure water.

[edisonghc]

Thank you so much for the troubleshoot!

So update on this guy - I have mounted it beginning of June, 2-3 new growths matured within a month or two, but since then it has not given me any new growth (or flower, neither has any old growths died or browned). And there isn't any obvious vigorous root growth.

The temperature has been around mid to high 70s, sometimes 80s. Average about 50-60 humidity, and moderate bright light. I've been trying to keep this mount always wet/moist. But there is a few times the mount has dried out for a day or two. I fertilize this together with my other orchids, about 200 ppm MSU every other watering.

This week, I've noticed some black spots developing on the newer growths... which worried me a little bit.

Does this Latouria has a deciduous habit?

I also just got a Den. spectabile this week from Lowe's, given it's also a Latouria, anything I should note for the care?

Any advice helps. Thank you in advance!

Originally Posted by estación seca

Welcome to the Orchid Board. For some reason this didn't show up back in June. Sorry you don't have an answer.

Imgur is saying traffic is too high so I can't see those photos.

Den. aberrans is in the Latouria group. They don't like to dry out at all during the warm growing season, and need just a little less water in winter. It looks to me as though it's been kept too dry. Many people here on OB stand Latourias in bark in shallow dishes of water. I would think every 5 days, under a fan, is not enough water.

They like high humidity. Setting a fan on it will make it dry out even faster. Most homes with central air conditioning or heating have plenty of air circulation. Unless you're growing in a humid greenhouse or terrarium you might not need the fan.

Perhaps it has been too brightly lit. I wonder whether those spots might be burns from heat or excessive light. Your humidity range isn't high enough to promote fungus, so I don't think your plant has fungal issues.

I wouldn't use a fungicide unless you know exactly what you are treating and know the fungus is susceptible to the fungicide you have. Many Dens are highly sensitive to the copper in Physan. It can damage leaves.

It needs regular fertilizer with all nutrients, not just cal/mag, especially if you are using pure water.

[estación seca]

I think your plant looks pretty good. Spectabiles prefer warmer temperatures but are otherwise similar. And much bigger. Latourias normally keep leaves at least 2-4 years if happy. They are evergreen, not deciduous.