If you have the ability with your camera/phone to get a really close-up picture, it would be more helpful. Having said this, it could be soft brown scale. Do the individual "spots" look like a plaque and oval and raised in the center? If so most likely scale. Jeff had made a suggestion that I used and it worked: spray your plant with Windex, wait a few minutes and wash with water. Obviously, you want to be sure prior to spraying anything.

Very common infection on that species of Pachycereus... I lost several plants to that scale... common particularly if your plant is not in full sun all the time. Hose or rub it off now and keep it off, or you could lose your plant.

As Howard said, that's scale and that's one treatment. Do the spraying of Windex / 409 while your plant's shaded for a day. Let sit 10 minutes after spraying, then blast with a hose - they should peel off easily. Let the plant stay in the shade for a day, then place back in full (?) sun - at least that's where it should be growing.

That plant could likely need a repot into a straght-sided pot, but you can wait until spring to do so - that's the best time.

It's in as much sun as the rest of my succulents/cacti which is at least 6 hours or more. When you say "straight sided pot, do you mean a square or rectangle? Just curious, why? I will try the windex tomorrow. One more question, what do I use to rub the scale off? Old toothbrush, my finger? Thanks so much.

I mean a conventional, cylindrical terra-cotta pot. It's far easier to repot from one of those than it is a recurved pot (which is what yours seems to be).

You use nothing - let the chemicals do their work and the blast from the hose will remove them. No scrubbing needed, as you will see in particular since your plant's sides are flat.

My goodness!

That's really scale?

I would have never guessed from that pic!

Can you get another close up just so I can see?

I mean I've seen scale, I thought I'd seen it get bad...I don't think Ive ever seen it that bad.
It's hard to conceive!

With no place to hide they should be easy to wipe out.

You must be a good grower for your baby toes to look so nice!
10 years of growing that plant and I've yet to have a plant look even respectable for more than a few months...

Here's a close up from my phone. Tried running off with my finger and they came right off. So I will try the windex next. Thanks for the baby toes compliment. I have never been able to grow them until now. Purchased 3 small ones from a Home Depot, planted them together, put the sea glass around them and left them alone.

Yes, that's a bad case of scale alright.

Glad to hear Howard suggested the Windex. I haven't tried it, yet, but read that it works great!

And your baby toes do look great!