That is a real shame! Sorry, Nil :(

I hate that. I have operated and treated with success but I do it only when the lesion is still barely a stain and slight roughness. I once bought a young Aloe clavaflora and when I got home I found that telltale yellow stain on the under side. It was my first experience with the mite and i tossed it in the dumpster. It was slight. Now I would try to operate and treat but I hadn't bonded with the plant yet and my collection was clean. That plant of yours has so many surfaces to treat and watch over. I would probably toss it too.

Stush is correct about 3 in 1. I have 5 Haws and Aloes that together got a nice infestation of spider mites, but a decent flush with Bayer 3 in 1 seemed to do the trick. At least they aren't in their death spiral now. I am hoping for some early October growth (here in Florida, a good time to grow). Another Haw was too far gone, I'm afraid. But overall, Bayer 3 in 1, which I used faithfully on my outdoor shrubs, has proven pretty good for nasty pests on my potted plants on the lanai.

Bayer 3in1 does nothing to aloe mites. It works great on spider mites though. Aloe mite is an eriophyid mite that is inside the plant so topical treatments aren't going to be very effective.

Some aloe don't show symptoms of aloe mite. Those are the only ones I'm interested in because Aloe mite is such a huge problem here. So when I grow aloe from seed I get rid of the ones that show damage.

also, getting the necessary chemicals to effectively treat aloe mite in CA can be difficult.

I did treat aloe mite with surgery and Sevin. BUT it was one small pup. all sides were visible. I quarantined it and it is two years with no repeat own it or on any other plants. We have aloe mite in Texas but no where nears as prevalent as California. I have not bought Forbid or Physan yet. One of my favorite growers is struggling with it. All the plants that have come down with it came from him. Maybe that is just a coincidence. Most were tiny and I tossed. Do you ever try to treat and with what ?

Can someone explain to me what I should be looking at in that picture?

For me, too. Is it the clump of puffy-looking growth in the middle of the rosette at the bottom? There are no early signs of it other than that?

Pagan

At the base of the bud is some squirrelly puffy stuff. Aloe mite likes growth points, joints of leaves, Buds, flowers. It also likes the margin of leaves and the center edge on the back if the leaf has one. It starts out as a yellow stain and then gets rough on the leaves . Bugs just grow in all bilbous.Here is A LINK On ALOE MITES

I don't bother treating. It is everywhere around me and the thermals carry them right up the hill to my garden. Treated plants just get reinfected. The only solution for me is to get rid of aloes that show damage.

Here are some A. brevifolia down the street from me.

Do you find certain aloes more susceptible to them and some more resistant? We are a decade behind in the aloe mite infestation.

Definitely. arborescens and brevifolia get hammered. Others will have some damage like in the first pic that will sort of come and go. And some never show signs. It's an auxin like response by the plant that forms the galls. So I think it's not a question of whether the plant is susceptible to infection but whether it has an unsightly reaction.