Utah State University Extension
Caused by a soil-borne, fungus-like organism (Phytophthora), crown and root rot occurs worldwide on almost all fruit trees. This pathogen is present in most soils, but only causes infection under optimal circumstances— high soil moisture or standing water, and susceptible host tissue. Once trees are infected, there is no cure.
Murray, Marion and Alston, Diane, "The Backyard Orchard – Plum Pests" (2011). All Current Publications. Paper 973.