Looking at problems posed by excess soil and mulch around the base of tree:
Mulch and soil should not be piled against the stems of trees and shrubs.
When performed correctly, mulching is one of the most simple and effective practices to maintain plant health, improve growth, and enhance vitality.
However, trees should not go into the ground like a telephone pole does. Stem tissues are not intended to remain constantly moist from mulch or soil accumulation. Insect and disease infestations, as well as girdling roots often develop on trees with excessive mulching or soil accumulation.
This post first appeared on https://www.bartlett.com/