Cattleya with diseased new growth
 

I have previously posted ref my Cattleya orchid. I was really pleased recently to discover new growth. However, while the growth has been steady, I am now really concerned that the growth is becoming very diseased. I water the plant once a week, with slightly warmer water than pure tap water. Plant looking very healthy otherwise, so any ideas appreciated? Thanks

The new growth looks anemic...might be a nutrient deficiency. Maybe. By anemic I mean the color is pale and sickly looking for most catts.

Too cold and damp could also be the root of the problem.

If it is cold/damp in your area then try cutting back on water. Also if you grow indoors, there may be problems related to excessive environmental dryness and media being too moist or too dry. Try Cal Mag(calcium Magnesium) supplement if available.That often helps. I do not remember instructions but the bottle should have it.

That looks the way new growths with calcium/magnesium deficiency often look. If it is cool or your media not open and airy, watering once a week in winter may be too often. Is it drying out between watering? It looks to be in a fairly large pot for the size of plant so it could be staying wet and causing root rot or fungal issues.

You haven't said much about current conditions and care, but basically agreeing with comments above. Perhaps needs more light, maybe more warmth, possibly nutrient starved, but hard to say since we don't know what you're doing now. Since the mature pseudobulb is shriveled I also wonder about root health. But most importantly, if those black areas are spreading the whole growth needs to be removed.

That looks like classic calcium deficiency. It tends to show itself when the plant is growing, especially if it is cold and wet.

See: Images of Calcium Deficiency on Orchids

and http://staugorchidsociety.org/PDF/20...ps-Calcium.pdf

To minimize fungal infection and spotting on new leaves, provide the plant with calcium. Especially important during growth. This can come from several possible sources:

Readily soluble sources:

Cal-Mag (calcium-magnesium) supplement (works, but can be expensive)

Gypsum, dissolved about 2 or 3 cc per 4 liters water, or 1 tsp/gallon (builder or hobby store Plaster of Paris is gypsum with the water driven off, and can also be used; gypsum and plaster are cheap) I usually mix in about the same amount of Epsom salts too. I mix maybe a half liter of this solution with 4 liters water (or a pint per gallon) that I use for watering, provides Ca, Mg, and S.

Calcium nitrate (sometime you can find this in garden centers)

Less soluble sources (provide calcium steadily over long periods of time, mix in with potting medium):

Limestone chips

Eggshell

Broken sea shell chips (clam and snail shells are better because they are made of aragonite, a more soluble form of calcium carbonate. Oyster shells are OK too, but are made of calcite which is more slowly soluble)

I would give it a dose of calcium and magnesium, as others have said, but also some iron.
It would be helpful to know how you are growing it. Cattleyas, while in growth, like warmth, a very bright window (with some direct sunlight) and fertilizer (I usually use about one fourth of what is recommended, but I also add Calcium, iron and Epsom salts). A good medium for these is something very open. I like LECA or red lava rock as it doesn't decay and become compact around February, like the bark always did for me.
If you lose this growth, it should send out another, eventually, with proper care. Good luck!

2 NEW SHOOTS...WHAT NOW?!
 

Having given my previously sick plant some extra feed over the winter, I am being rewarded with 2 very healthy and vigorous new shoots. We had had a reasonably warm summer here in scotland, and the plant was moved to the bathroom recently, so this has all helped I think. My question to all the experts out there is what do I do now...will I cut back the old leaves, or let them die back naturally. Also, if I cut, do I cut the ones that have the new growth? Many thanks.

Good job growing!

Don't cut leaves nor pseudobulbs off orchids unless they're diseased. Just let them age naturally, turn brown and fall off on their own. Sometimes you will need to cut off old, dead pseudobulbs. Most people do that when repotting so as not to disturb the plant in the pot.

Cattleya leaves normally live for quite a few years before browning and falling off.