Jose Marti cattleya - black spots and casing, drooping
 

Hi
I am a total beginner, and I seem to be killing my first orchid - a Jose Marti Cattleya.
It has black spots on its leaves. The casing on one of the new shoots has turned black, and the whole shoot has dropped.
Another shoot has drooped and seems to be rotting.
I have been watering once a week. It sits a bright room which gets morning sun, but doesn't get much direct sunlight. I live in the sub-tropics so we have comparatively high humidity (between 60 and 90%).
Please help me rescue this poor beauty! It is too much or too little water? Not enough light?
Any advice will really be appreciated!

That's a bad case of scale. The spots are the mature adults and the white fuzz are the immatures. That white fuzz looks like mold but the young females mature and become those round bumps on your leaves and lay eggs under their protective cover. You can scrape the mature ones off but you need to use an effective pesticide to deal with everything in the nooks and crannies where you can't see. Usually a systemic with imidaclprid works well for a bad infestation.

You should also get this away from any other plants as they easily spread. If it was near them, you should inspect and treat them for scale too.

Thanks so much. I didn't realise it could cause so much damage! I guess I'll try wiping it down with rubbing alcohol?

I just added more comments above. Wiping with alcojol might help, but they can be in the media and in nooks and crannies where wiping won't get too. I recommend a spray that will run into nooks and crannies and into the media. I don't know what you have access to but I often use Malathion (a contact spray) to kill everything on contact and then follow thru with Merit (an imidacloprid base) as a systemic to deal with eggs that will be hatching. In my opinion, scale is the hardest pest to get rid of and 6 months later, when I am sure it is gone, it can show up out of the blue. Multiple treatments will also be necessary.

---------- Post added at 12:32 PM ---------- Previous post was at 12:11 PM ----------

I'll also add, the casing on new growths can turn black or brown and that is normal. You can very carefully peel it back, maybe by slitting it first to avoid damaging the growth and make it easier to come away. Remove any dry casing and bracts as it is a good place for scale to hide.

I'll phone around the local nurseries for sprays. Thanks so much

God luck and keep us posted as to how things are going.