Shoestring Root Rot, caused by Armillariellia mellea USDA Forest Service Forest Health Protection, Southern Region Shoestring Root Rot, caused by Armillariellia mellea Importance. This root rot fungus causes major losses throughout the United States. Windthrow of infected trees in urban and high-use areas creates safety hazards, contributing to the economic importance of this disease.
Additional losses occur from reduced vigor in both conifer and hardwood species.
Identifying the Fungus. A. mellea produces thin, black rhizomorphs that grow on the root surface. The rhizomorphs resemble black shoelaces. Identifying the Injury. Shoestring root rot mushrooms.