Q.Is the crushed stone under my tree killing it?
Using crushed stone to keep the mud down under my magnolia tree. My wife is afraid it will kill the tree.
The crushed stone is likely not harming or killing the tree. It's not helping the tree like the natural leaf litter, or a mulch layer of organic matter would.
One important consideration is that the soil base is not compacted, and that the rock is not driven over with vehicles or otherwise compacted into the mud layer, forming a mixed aggregate concrete-like layer that interferes with water and air movement into the upper soil profile.