Yellowing Zygo family leaves

[Syrinth]

Hello everyone, I'm hoping you all can help me! I hav three zygo-family orchids, zygopetalum australia advance, propetalum mathina elizabeth, and zygonisia snow birds.

For the past, oh say month now, they've had leaves one by one turning yellow. First a single stripe appears in the middle of the leaf from tip to bottom, then the line spreads and gets thicker until the whole leaf is yellow and drops off.

Only my zygo family orchids are effected by this, only older leaves are yellowing, the leaves from the more recent growths appear to be fine.

My thoughts are issues with sunlight, fertilizer, or aging.

Sunlight - They're in a South facing window, about a foot away from the glass. The window has a blind on it that cuts out about half of the light I'd say.

Fertilizer - Might be giving them a bit too little fertilizer. Looking at my notes, I've been maybe doing it about once every two weeks because I wasn't paying attention.

Age - Although it's only the older leaves that have been dropping, it's been a lot of them, and from different pseudobulbs. I find it suspect that they'd all be dropping like this if it was an aging issue.

I'm hoping it's just a fertilizer issue. That makes the most sense to me, but I'm worried because I've been trying to fix it by ensuring they have fertilizer *realized something was WRONG last week* Maybe I haven't given it enough time to fix itself?

[cjm3fl]

These guy seem to like bright light, somewhat cooler temps and do not want to be dripping wet.


Here's a discussion on the Orchid Board that you might find helpful:
Max. Zygonisia info...

[estación seca]

I think they drop older leaves, eventually.

[FourN6]

I have a Zygonisia Blue Birds doing the same thing. I posted a picture just a few days ago. It was suggested I wasn't watering enough.

I also have a Zygo. Advance Australia but her leaves are fine right now. Both plants are in the same window...a tinted west facing window...for now. The biggest difference is my blue bird is potted in bark and my Aussie is in moss.

I really don't have any suggestions since I'm still trying to figure out my plant's problem but if you get a good answer Id love to hear it!

[No-Pro-mwa]

Do you have good air flow?

[ramonypony]

Are the roots in good shape? If it recently lost roots my zygos have been known to drop old leaves at an alarming rate. Mine tend to shed their 3 leaves per bulb at about the same time when they're old. It doesn't sound like much of a worry.

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[blueggreen]

This is an old thread so I don't know if you solved your problem, Had the same problem with my phal and zygo,looked up use of Epsom salt and cal mag on orchids on the internet.

[Dollythehun]

I have three of these and a Zygo Advance A. My Zygo doesn't do this but the other three drop leaves regularly. Air flow is great, temps are moderate, and they are standing in water. I think this is particular to the tribe.

Blue green, do you have a link to the particular article you were referring to? If so, please post it.

[blueggreen]

if you go to YouTube do a search on cal mag for orchids or try yellowing of leaves of orchids,your growing conditions will be different from mine so the remedy maybe different.

[Dollythehun]

Bluegreen, I did a search. My results were not so certain as yours. Which specific site did you find spoke to the Zygo family? I would be cautious about YouTube articles in general. However, if this is true for Zygos, it would be very helpful information.