Cymbidiums with yellowish spots
 

Initially I thought I has some water spots on a leaf or two, but it spread like wild fire. Suggestions on how to cure my plants? They are ALL affected.

Thanks!

Looks like you got a case of scale there... Very difficult to eradicate once it's already established. I had to pick off each bug from my phals and it significantly damaged its leaves. On my other tropical plants (not orchids) I just cut off the affected leaves. Good luck!

Try to find a systemic insecticide, preferably a granular.

Imidacloprid or thiacloprid take care of them.
Bayer has some products based on them.

The long term solution is a systemic insecticide. To knock the population down a bit first, get a soft toothbrush, or 1-inch wide paint brush, and mild dish detergent (diluted), and gently scrub as many of the same loose as you can. Try to Target nooks and crannies too, and bottom as well as top of leaves. Rinse thoroughly with tap water after.

You may see yellow dots where the scale used to be. Those won't go away until the old leaves are replaced by new ones. Don't worry about it too much.

Once the scale is cleaned up, you still need to treat with a systemic insecticide. Follow the manufacturer's instructions.

You have a big problem that you do not get rid of easy, throwing all the plants and starting a new adventure gets you cheaper. What you see is just the top of the iceberg.

Since cymbs are terrestrial orchids, I assume the OP's plant is in some type of "soil" mix. I suggested granular improcloprid because of the ease of use and effect on the root system up. It is getting harder around here to find Bayer 3 in 1 spray.

I use the spray (concentrate) and dilute as needed. If you like the sprays, you can always get from Walmart's online store.

I am curious which granular product formulation you use? Do you prefer it over the spray?

I get it from our elevator. It originally was labeled as Marathon. My jug is a generic brand. It was not cheap, but goes along way. I like being able to scoop it directly on to the media. It won't work well with bark but, is fine for moss or terrestrial mixes. I also don't use it outside anymore as years ago I suspected ( although my supplier denied it) that it was deadly for pollinators.

When I must, I spray but, unless I order from Amazon (or Walmart, as you suggested) it's hard to find. Now the formulation is based on a synthetic pyrethrin.

I have't had to use them on the orchids yet, but for our other outdoor plants I've had good luck getting rid of scale using one of the natural/organic insecticidal soap or oil sprays. They require diligent repeated applications, but I really don't want to kill non-target insects and spiders.

I have 50 plants - throwing them away is not an option.

Why would you do that?

I really can't understand how some people advise/think to throw away sick plants when these are excelent opportunities to learn.
Obviously there's some cases where this is the only option but only when all the other possibilities have been tested.

Again, use imidacloprid and you'll see improvements in a short time.

The roots (there they multiply) are infested with scale, so you have to change the soil probably also being infested with a fungus or virus. Next year you will not see flowers from the plants. The insecticide also costs and imidacloprid is a neurotoxic (destroying bees is banned in many places around the world). It's an option, I have it, and I have learned it.
How could 50 plants be infested and you do not notice?
Probably the least infested you can treat, but with very infested you will have to learn the lesson. I personally grow orchids for me to enjoy when they bloom.
I think with $ 10 you can buy a healthy plant.

With 50 badly infested plants your only hope of success is to use a pesticide.

I'm very light handed with pesticides but in this case, I'd spray and spray diligently for a month or more. Granular would be great for maintenance.