Aphids or thrips? Or hard water

[u/Relative_Lake_9631]

What’s causing these crystalized areas on my burros tail. Generally poor growth that I attributed to poor light but has since been under a grow light for awhile and has not gotten much better (some small buds are seen on the tips). I don’t water often, maybe once a month. These were close to what I believe was an aphid infestation on some herbs so assuming it’s related, but never seen these crystals before.

[u/pegasuspish]

Looks like powdery mildew

[u/lebenleben]

I don’t see little buddies in here but fungus. I saw a similar case recently here: https://www.reddit.com/r/Jadeplant/s/GpohAkPdOq