You're not supposed to mulch around fruit trees. I don't know if stone is considered mulch. I put weed cloth and then a layer of newspaper around the base of my fruit trees. No mulch at all.

But to answer your question: the dust won't hurt the tree. The rock itself may.

I my climate, you mulch citrus, just not right around the trunk or it could rot. Mulch at the drip line. You don't use rock mulch because it gets too hot and doesn't have the other benefits or organic mulch. A different climate could be a totally different story.

That said--I doubt the dust is harmful unless there was a ton of it (enough to bury the root flare) or the rock itself is actually kryptonite or something.

The dust is not going to harm your tree. Don't worry about it.

In all my years in horticulture, I have never heard the suggestion to not mulch around fruit trees. There is certainly no reason not to and all the same reasons present that encourage mulching around any other kind of tree!!

Mulch - whatever kind may be used - will not hurt and the dust coming from the rock is just that ......dust. Your tree and soil is being exposed to all manner of dust all the time. Just hose it off and don't give it another thought.

I would find out if heat and dryness would be an issue with a fruit tree. Regular mulch can offer moisture retention and coolness which may be beneficial to your tree.

Laura, weed fabric and newspaper are, strictly speaking, mulches. And since weedcloth is inorganic there seems no point in putting newspaper on top of it. Just using newspaper would do the job.

I think the issue with mulch and trees is the people who pile it a foot up the trunk.

The white dust on the rock is ROCK that got pulverized with all the jostling of the rocks.

I'd remove the weed cloth as well. It's pretty bad stuff, especially when it starts to degrade, which it will.