Too much sun for this Catt. or deficiency?
 

I have a pot with a couple NoID cats in it, one of them turned red, while the others seem to be doing fine. It seems a bit dehidrated too. I'm debating if I should pull that one out, I'm afraid that they are too intertwined in there and I'll have to cut some roots off. I just hate disturbing them like that. What do you guys think?

One more

It is borderline too much sun.

Where and how are you growing them? You don't mention how much light they get, nor what sort of fertilizing regime you use. I know that in non-orchid plants reddening of leaves or leaf margins is often associated to phosporous deficiency, but here it's strange that the other plants in the pot are fine.

The pot is in bright filtered light. It gets quite bright around noon but its shaded by a large tree and huge ferns. Right now they get fertilized every other week with better gro bloom booster 11-35-15, I also switch it up with orchid plus, 20-14-13.
What is even weirder is that these orchids have been potted together for couple years, but only about 6-7mo ago this one started to red like this. The rest seem just fine. Hmm, should I try to take it out and mount it? Or is it going to just make matters worse for the already upset plant?

Could be the community pot that's the problem. Maybe it's getting outcompeted by the other plants and starting to suffer.

Can it be a Magnesium deficiency? Do you guys use Epsom salt when you fertilize?

Magnesium deficiency usually has symptoms closer to those of nitrogen deficiency (yellowing).

I supplement with epsom salts, but that's mainly because the tap water in my area has somewhat low amounts of magnesium. I had a new Phal which stayed really pale looking no matter how often it got fertilizer, and the moment I started the epsom salts it greened up again. But that was completely different symptoms.

You could try reducing the light for some weeks in case it's that, and if the red doesn't fade then consider repotting it separately.

Ok will do, to think about it these guys have not bloomed for me in a while. Hmm...

It looks like too much sun to me also.

I would be inclined to leave it in the basket and not repot or mount it. It looks like a bifoliate and they don't like to have their roots disturbed. Bifoliate cattleyas also usually prefer brighter light than other cattleyas so I'm surprised that it's reacting like that. Bloom booster fertilizers contain large amounts of phosphorus and it can prevent the plant from absorbing other nutrients, especially magnesium. You may want to consider using you other fertilizer more often and the bloom booster only occasionally. You can try applying epsom salt at 1 tablespoon per gallon of water, by itself, not mixed with fertilizer, once a month for a two or three months and see if it makes a difference. The epsom salt is just a supplement so continue to use your regular fertilizer. I grow in high light conditions so I'm used to seeing some red on the leaf margins. I usually don't worry about it unless the leaf starts to burn.
The angle of the sun is changing as we get near spring so make sure the plant isn't getting direct sun during the middle of the day. Good luck.

Do nothing, you're growing this just right. Seriously, red on the leaves is what I shoot for when adjusting my light. I used to grow most of my Catts in VERY bright Hawaiian sun, which is far more intense than anything we get here on the mainland and they loved it. Just make sure you have good air movement around the plants so the leaves can cool off.

I just went and got some Epsom salt and will do a very light supplementation next watering just in case since I never done it ;) especially for some of the lighter colored ones

Quick update on the red Catt. I pulled it from the pot and mounted on fern block, wanted to see what was going on with the roots, they were prety much all dead and the orchid actually split into two. So after 3 months out of the pot the left side grew a nice new shoot with some killer roots!! Yay!;) the right side is still giving up on life. I'm putting a bag over the whole thing and adding rooting hormone to the fertilizer mix to see if I can get the other chunk to wake up fingers crossed:)

One more pic of the experiment.
Actually another interesting thing, I just recently got 3 bare root Catts and two of them are doing great one on fern one in pot, the third one also in pot with clay balls and some bark/moss mix is turning red. It's sitting on the same shelf, and same medium, under shaded tree no direct light. I'm really wondering as to what this is. Maybe it was grown in low light conditions and I should have kept it in the house and introduced to outside slowly?

I have ones that have red in the leaves. I like it as I think that means they are getting good light. I of course have also burned some spots on leaves. I hope this works for you.

Many of my cattleyas have red on the leaves and, as long as the leaves don't burn, I don't worry about it. You said you use a bloom booster fertilizer. I would recommend that you not use a bloom booster during the spring and summer. The high phosphorous can block other nutrients from being absorbed. I would recommend Southern Ag 16-3-16 6 Ca 3 Mg from Broward Orchid Supply in Hollywood, FL, or Norman's Optimal Orchid Nutrients mixed with MagiCal cal/mag supplement. You can get both those products from Green Barn Orchid Supply in Delray Beach. I recommend that you buy the book Florida Orchid Growing by Dr. Martin Motes. It's very specific to growing in Florida. Also there are many great orchid societies in this area. I belong to the Ft. Lauderdale Orchid Society and the Plantation Orchid Society. There are other societies in Sunrise, Davie, Pompano Beach, Margate and on and on.

Red flowered Cattleyas tend to turn red in good light. I wouldn't worry about it.

Honestly, I think this is a bad idea. There's a good chance that you'll end up killing the healthy side with only a marginal chance to perk up the sick side. Florida is already crazy humid and cutting off air circulation is only used as a last ditch effort to heal plants with no roots. It is a very efficient way to kill orchids that don't need such treatment. You'd be better off leaving the healthy side alone and doing spag n bag with the sick side in a separate pot.

I think it's sun/heat damage.
It is not getting too much light, but it is beyond that. It is being damaged by it. The color and the texture of the leaves all indicate that.
Move your plant to lesser light and may take a while to recover.

Yea, I can see what you are saying. I'm just noticing how fast things get bone dry here in FL, the bag is open on the bottom and is just an attempt to hold a little extra moisture in. But your right the new growth should do fine from here, and the not so much alive chunk should be treated separately. I'll be monitoring, how they do, n probably split them when I find a moment.

Here's a pic of the new one I got dry root. I moved it inside to the patio now. Maybe it's like a moisture retention ability vs heat issue. Seems like the weaker plants are prone to this heat damage. Tho two others I got same day also dry root, are doing fine on the same spot.

Wow~ orchid hobby must really be very big down there.
I used to visit Plantation, Sunrise, Davie on a regular basis, but never realized it, although one friend somewhere in Ft. Lauderdale did have a large blue vanda hung on the palm tree in his backyard.

Kasiopea,
Don't forget, Cattleyas need to dry out completely between waterings! Bone dry is not so bad!

Dehydration, roots are out competed or otherwise not working. Definitely remove and repot if you want to try to save it.
The deficiency and sun excess does not make sense since similar plants in same pot are fine.

I agree with David...this orchid is getting all the sun/light it can tolerate. Any more, and the leaves will burn! Been there, done that. BettyE.