I can't really tell from the picture, but google 'scale' bugs and see if that matches what you're seeing.

I've seen spots like that though that turned out to be just injury/insult to the plant.

Superficial and nothing you can do about it if that's the case, but more importantly, harmless.

If scale though, I would want to treat, however, I do not grow this plant, so I can't comment on how or what to treat with =/

Hopefully someone more experienced with this plant can offer thoughts

=D

Thank you hookilau.

I went and spoke with someone at my local nursery. He said it could be scales but then he asked when did I plant it. I just planted it about a week ago. He said scales shouldn't be attacking so early. Then he mentioned maybe I was over watering it. I think I probably did water it too much. Anyways, he said to use some rubbing alcohol and que-tips. See if they come off. I then was chatting with a friend who also said it might be scales. But she said to use dawn soap and a toothbrush. Then I did a Google search on scales. Some people say use half soap and half alcohol. I ended up using just the dawn soap and toothbrush. I had to scrub it pretty good with the toothbrush and use my finger nail a little. Think I got most of them off.

Hopefully they don't come back. Sorry for the writing a book here. Thanks again!

greg

In the future, don't use soap. Regardless what ppl tell you and what you find on net, it is not the best to use it on plants. Soap will dissolve cuticular wax on the leaves, not helping the plant. Castile soap is made of olive oil, so it is safer to use on plants (but if purchasing, make sure it is vegetable-based soap, as Castile name is used, unfortunately, loosly...) Rubbing alcohol is enough for scale - but if you had to rub/scrub hard & also use nail, I doubt it is scale. Scale come off quite easy. Next time you see similar spots, test first if it is scale - take a cotton ball or tissue, moisten it and wipe off the 'spot' - should come off easy and if squished, you'll see blood...maybe gross, but at least you know what you need to do.

BTW, were there any marks-damage left after scrubbing?

(Edied to add: I just re-read posts and noticed that Crenda already mentioned possible damage on the leaves - that's what I was asking for).

Thanks Rina and Crenda. The cactus is planted outside. It's about 2 feet high. I think I washed all the soap off well. How would I know if it's burned?

There are little holes where I scraped off the dots. Also there is a lot of white/washed out swirl marks from the toothbrush. I went over a lot of the surface. Even parts that didn't have the spots. Didn't think it could hurt. I must of stripped the cactus's wax. This makes me sad ..

Do you think this cactus might be doomed that the wax has been stripped and the tiny holes?

I'm thinking to just cut it to the lowest point that the marks and holes are. Let it regrow?

It may not be doomed, but it's a lesson for the next time...Just pay attention to it for a while. I wouldn't cut unless there is some serious problem (or you just 'hate' how it looks).This plant does get all kinds of marks - it does cork too (hard, brownish/tan colored skin that starts at the bottom - on many other cacti too, and it is natural). It often sends out aerial roots that are hard & wiry - I usually cut them off, they could get long.

If there are small holes left, it was either some small damage scabs that you got off, or oedema Crenda mentioned.

Plants don't have perfect surface, and many things/mars/scars are not disease or insect.

Urgh , now I woke up to see this. It's horrible. :( Yesterday it didn't look so bad.

Could that browning be burned?

Yes, there is some surface damage. Lets hope that all it is - maybe keep it from strong sun for few days? -(if in ground, just put large plant or something similar in front of it to shade) not sure, didn't have to deal with this kind of situation.

It does look like some burn, it may scab over like a thinner (parchment-like) skin. The holes will most likely scab too, and will look like bigger version of what was there before.

This is a vigorous grower, and will likely continue growing in spite of damage. I see new tip there already.

Old parts/arms of my plant look much worse, the new growth is nice and green and quite smooth. Different succulents would have been much worse - if that is any consolation :)