I suspect (but do not really know) that your problems come from the Coel. speciosa parent. I have no trouble at all growing the "Cool" growing members of the family outside in a shade-house all year (it got down to 2C one night this winter) but failed miserably trying to grow some of the species that need warmer conditions.

Purchased Coel. Bird in Flight at a show a few weeks ago and put it in my slightly warmed up glass-house.

Sorry, not much help.

Have no idea. Part of me wants to say something about it looks 'funguly.' Is it getting too warm?

Another part of me wants to say something off with nutrition. Maybe try a little Epson Salts in your water and see of the yellow disappears.

I suppose virus could be another guess.

I understand your frustration. I hate when something happens like this and it is not clear the cause.

Jane

Thanks to both of you for your replies. I grew it cool in the winter and it was unhapy. It it outside for the summer, which has been very mild for us. Highs in the upper 70s and lows in the low 60 to high 50s. I use a fertilizer with micro-nutrients, but maybe it needs more magnesium. What ratio should I use?

I will give the fungicide a try again. I tried previously with no results, but I thought the spots were leading to a secondary fungal infections.

Hopefully something will stick. It is growing but al the leaves turn eventually.

Those little brown spots in the last photo suggest something fungal or bacterial. I could be wrong, I can't see it close enough. I would try using a fungicide which should take care of either.

Did you see this months issue of Orchids? Interesting article on Cal/Mag deficiency and how it appears on Catts. You are using RO which is what I have used. I am now using rain water which is also deficient. The suggestion is to have the water tested for Cal/mag and adjust your fertilizer accordingly.

I might just start adding it in small amounts to some of my plants I'm noticing having leaf spots which are not responding to sprays.

If you have this months issue, give it a read.

Jane

I read the calcium deficiency article in Orchids. The St. Augustin Orchid Society also has a really good article on the web from a couple of years ago which caused me to adjust my fertilizer my while back. I think both articles are authored by the same person. I need to check on that.

I fertilizer my ro water because there is close to nothing in it. It registers about 5 ppm TDS so it is pretty close to pure. I use low dose of the MSU fertilzer. I also have a CalMag supplement that I use monthly. I am hoping the mag in the espom salt would be helpful. This Coelogyne is my only orchid that does this. My other Coelogyne are fine. I am going to try the funicide again.

All of the leafs start like the bottom picture and end like the one above it. The spots are not wet or mushy like you would think. The leaf actual gets rather dry. Then falls off.

I wrote to CalOrchids where the Coelogyne was purchased. Below is their reply for reference:

"This Coelogyne can often get spots on the leaves. we found that the plant grew better out of doors for us and got less spotting when there was cooler conditions with good air circulation. I do not know exactly what causes the plant to spot as it seems to spot easily and later grow out of it easily. We have discontinued stocking this plant because of this."

I am not sure how much more I can change about the culture is terms of temp and air movement. It spots outside and inside. I am still going to try the fungicide and cross my fingers for now. If the spotting does not discontinue, I am not sure what I can going to do with this orchid.

Wow, that was very interesting. At least they were honest and have not figured a way to stop the spotting.

Good going!

Jane