I use Bayer Tee and Scrub concentrate.

Do not use "RTU" (Ready To Use) spray bottle versions of any pesticide. Always use concentrates to be mixed with water.

My "Bonide" Neem Oil concentrate (70% pure) doesn't specify for Scale, but is safe to use on Adeniums. (There are 99%/100% purity brands available, such as "Dyna-Gro".)

Depending on what type of Scale you're dealing with, you will probably need to treat your plants up to 3 separate times in order to kill newly hatched pests.

With "Hard Scale", I've literally had to use "Hand to Hand Combat" with them. I had a Gardenia Bonsai with every Centimeter of bark covered w/ Hard Scale. I meticulously went over the entire plant with a toothpick and pocket knife, prying and killing every individual little bastard; one by one. Then I sprayed it off w/ water, and finally treated it w/ pesticide. I am proud to say, I was successful!

Some people will say, when dealing with Hard Scale... If you're not particularly fond of your plant, bag it up tightly, and dispose of it as far away from your home as possible.

Rob

I have used Neem Oil for spider mites and Aphids. I mix it with water and a few drops of Dawn dish soap. Definitely has not caused injury to the leaves. Always done in evening when sun is off of them.

Rick

I use neem oil and have been using thyme oil this year because nematodes

UPDATE 10/5 -

I climbed up on my step stool yesterday to look for something in my ferts supply cabinet. While moving stuff around; I noticed a loose piece of paper on the top shelf. As it turn's out, it was 2 pages of the instructions off my Neem Oil container.

I read through it, and the info it contained; did list Scale as one of the pests affected(?) by Neem Oil.

So there you go.

Rob