That looks like a whitefly infestation. Are there little white bugs flying around when the foliage is disturbed?

It looks like whiteflies to me too. Sometimes they leave little circular patterns of the white stuff. When I get them, I cut off the affected foliage if it won't be too noticeable, scrape up the leaf litter, and water in worm castings. I don't know if the worm castings are hocus pocus or if there's a chemical in them that the whiteflies find distasteful, but I eradicated them from my canna lilies. It may have been just removing them physically that did it.

This is easy to treat: blast hose water on top and bottom of leaves. Do you see white concentric circes? That is the stage of whitefly you need to blast (hard) with water. It breaks the cycle. If you do cut off infected leaves/branches, bag them up so the whitefly doesn't get spread around.

I once had an entire tree covered in this stuff. Everybody said cut it down, but simple water blasting saved it.

I poked around the tree today looking for whiteflies, none around. And the castings didn't strike me as round, but I wasn't looking for that so I'll look again. You guys have me hoping it's this easy...

I'm kind of suspecting glassy winged sharpshooter, as I came across a photo on the UC pest site, and realized that I've noticed (something very much like) them lately on an adjacent pomegranate. The sharpshooters also leave a white residue but I'm not sure it's a match to the heavy webby dust all over my tree. I'll look for their eggs and the scars the eggs leave on the leaves, tomorrow. If they are sharpshooters it seems like targeting them with wasps is recommended. Hmm that might make it time to call the arborist for a visit.

Here is a link that might be useful: UC Davis Glassy-winged Sharpshooter

You may have sharpshooters too, but that sure looks like a whitefly infestation to me.

sbmw, the concentric circles are white, laid on the leaves, and they are the eggs of the whiteflies. Worm castings are a fertilizer (worm poop) that supposedly helps plants recover from a whitefly infestation. Here's a link to the concentric circles we are talking about.

Here is a link that might be useful: {{gwi:549767}}

Thanks for the feedback. The spiral photo was helpful in my understanding what was meant. And I don't see anything like it on the tree. I took a better look and some of the worse-off leaves are dappled with white spots below the fuzzy white stuff that flies off so easily, and the tips of those leaves are burnt. I tried to take some photos but my cell phone delivered fairly fuzzy shots.
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I have not seen a single whitefly and no eggs visible to my eye. Just a stormcloud of white dusty stuff that is airborne when I disturb the leaves.

On the Pomegranate tree right next to it, the bugs look less like sharpshooters than I thought. Whatever they are, they are angry looking and they like pomegranate. Again with the fuzzy photos:

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I like the idea of hosing it all off and seeing if that's enough.

The insects are unrelated to the white stuff. It's hard to tell, but those could be assassin bugs. Some have a very, very painful bite.

I think it's a good idea to try to hose it all off.
Renee

Found your bug. They are leaf-footed plant bugs, pests of pomegranate trees. They bore holes in the fruit, ruining it. I would squish all of the ones you can find.
Good luck.

Here is a link that might be useful: Leaf-footed Plant Bug on Pomegranate

Renee, you rock. Thanks for chasing that bug info down. Yet another critter in the yard to deal with. But at least it's not the ominously-named Assassin Bug! Gotta look that one up.

Assassin bugs are beneficial in that they "assassinate" other insects, thereby helping you manage the pesky fellows.