Oak Root Fungus
Oak Root Fungus
Tap to view larger image


Remove all infected plants, vines, and as many roots greater than 1 inch in diameter as possible. Then planting resistant species is the only effective control.


Also called armillaria, shoestring, or mushroom root rot, this disease is active in wet soils, the fungus invades the roots of many plants. Symptoms of the disease vary. The fungus: creamy white, fan-shaped layers, with a strong mushroom odor, growing beneath the bark near or below the soil level. Clusters of honey- colored mushrooms may appear around the base of the tree in fall or winter.
Oak root fungus doesn't spread through the soil; it moves from one tree to another when healthy roots come into contact with infected ones. It can survive for at least 30 years in dead roots below ground.

Target: Primarily woody plants, especially oaks and fruit trees.

Damage: The trunk is girdled. Dull, yellowed, or wilted foliage is usually the first sign of trouble; infected trees usually die back slowly.

Control: Resistant plants, landscape granules.

Notes: There is no cure. Remove dead or badly stricken plants, trying to dig out as much of the roots as possible. You may be able to prolong the life of a plant by uncovering the infected root crown, then leaving it exposed to air and giving little or no water.