Please settle a discussion I am having: I have stated that mulch should NOT be placed up against the bark of trees and other plants; that there should be a couple of inches for the plant to breathe and prevent pests from breeding.
Prince George's County Maryland
You are correct. It is our recommendation that mulch not be piled up against the trunks or base of plants. Here is a page you can share, with further links as well:
Thank you for your confirmation and the links but it still doesn't answer the the 'why' you should not do it.'
You answered part of the 'why' yourself.
It holds moisture against the plant's main stem which can lead to disease or pest problems, including hiding places in the winter for small rodents to injure bark without being noticed.