Mushroom-Shoestring Root Rot

By The Old House Web

Mushroom-Shoestring Root Rot

The mushroom-shoestring root rot is widespread in the north central states.

Symptoms: The most noticeable symptom is a gradual decline in the vigor of the tree or shrub over several years, followed by yellowing and dwarfing of foliage, wilting and death. The cause may be confused with other wilts, root rots and decline. The diagnostic symptom is the cluster of honey-brown mushrooms that appears at the base of the plant in rainy autumns. To confirm the diagnosis, dig the roots and examine them after the plant dies. When the mushroom root rot is involved, slender, dark, shoestring-shaped fungal roots should be evident growing on the surface of infected roots and outward into the soil. A careful search and close examination is necessary to distinguish the shoestrings from plant roots.

Cause: The fungus Armillaria spp. exists in the soil, feeding on buried roots and stumps for many years. When a tree or shrub is mildly stressed by drought, poor site or other causes, the mushroom-shoestring fungus can send a shoestring as far as 8 feet through the soil to invade the plant roots. The fungus grows between the bark and the wood, forming white, fan-shaped patches of fungus that smell like fresh mushrooms. The infection destroys the root function and causes the tree to decline. Often the disease is called oak root rot because it frequently occurs on oak in native sites. The fungus can attack many tree species, however.

Control: If possible, ornamental trees and shrubs should not be planted on recently cleared woodlands where the mushroom-shoestring fungus usually occurs. When grounds are contaminated with the fungus, soil fumigation is effective in removing it.

Go To Top of File               Main Page for this Data Base

Search Improvement Project