Editorâs note: This article, courtesy of the Kendallville Tree Commission, is from the Purdue University Landscape Report, used by permission. Usage of mulch at the base of trees is a very common and recommended practice to protect the trunk from mower damage, as well as improve root conditions by preventing weed and grass growth in the root zone. Mulch also increases moisture retention in the soil, and improves soil quality as it breaks down over time. However, there is such a thing as âtoo much of a good thing.â Over-application of mulch, in the form of piles or âvolcanoesâ mounded up the trunk of a tree, will prove detrimental to the health of the tree and can lead to premature death. This is an unfortunate and fairly common occurrence in the landscape.