Virus, Fungus or What ?

[Anton]

I had a look at my Zygopetalum today for the first time in a little while, (been away on holidays) and noticed these black markings on the leaves.

Is it virus, a fungus, mould or something else ?

Thanks in advance.

[Cynthia, Prescott, AZ]

Looks like sunburn to me. Do I see a patch of green across the bad area that looks like a Cymbidium leaf might have kept that section shaded? Are you growing this outside or in a window? Cynthia

[Anton]

It is actually a zyg and was inside and flowering when it started.

It started clearing up so I put it outside when the flowers had died, and it is under shade cloth. We are just coming out of Winter, so definately NOT sunburn. )

But, it is surrounded by cyms, and as I have been away can't be sure of went on for that week. :/

The arrow shows it hiding in the back.

[Anton]

Trigger finger, meant to add an attachment, too quick.......

Here is the picture of where it hides. I also didn't get a chance to proof read before it went, and will correct myself, I originally thought you wrote that it look like a cym leaf, but I was WRONG, that's NOT what you wrote at all, so I am correcting myself in this post

Is this a good or bad position FOR IT ?

[Anton]

Cynthia, I had a close look at the photo of the leaf and actually missed that band across that you picked up.

See what happens with familiarity, and how good this forum is. It's great having fresh eyes looking at things that are easily missed.

Pity it's not a forum about "forests and trees". ha ha

[Cynthia, Prescott, AZ]

Well, the only other thing that came to mind was frost, but you have such a mild climate that I dismissed that. How about a chemical burn that involves a heightened sensitivity to light, hence the shadow. Did you say that this happened while it was in the house, or did it get worse shortly after you put it outside? I have seen chlorophyll loss due to giving plants too much sun and heat (normal levels) shortly after spraying with Neem oil, but nothing this bad, but I did see shadows like yours that clued me in to the fact that it was sunlight related. Unfortunately, I don't grow Zygos by choice, so I can't say much about their culture or sensitivities. Cynthia

[Anton]

Has happened inside as well as out. :/

The band across the leaf is a mystery though. The only liquid that's been on the leaves is pyrethrum spray, but that hasn't caused problems before.

We had frosts this winter, but as you saw, the plants are under shade cloth, and there hasn't been any heat baring sunlight to speak of, just typical cool, overcast days. It has been a mild winter, similar to your Fall.

[Cynthia, Prescott, AZ]

??? Let us have some feedback over time and let us know if this is out grown, or gets worse. Did you use anything chemical nearby that you didn't think reached your orchid? Maybe others have some experience that explains this or how to avoid it. Cynthia

[Anton]

No chemicals at all !

I await with bated breath.