Plum Trees With Mushroom-Like Growths

Oak Root Rot

• Oak root rot is a frequent problem in plum trees that have been planted in areas where oak or hickory previously existed. Caused by the fungus Armillaria mellea, oak root rot produces mushrooms that pop up from the earth as far as the roots of the tree stretch underground. These fungal bodies are a clear sign that the roots of a plum tree are rotting beneath the surface of the earth.

Symptoms

• In addition to the mushrooms, other symptoms of oak root rot are a chlorosis -- or yellowing -- of the leaves of a plum tree, a curling of the leaves and a browning of the foliage and stems. These signs of Armillaria mellea are the result of the weakened and diseased roots being unable to absorb and transfer sufficient nutrition and water to the rest of the plum tree. As the disease worsens, defoliation occurs and limbs die.

Mushrooms

• Below the surface of the plum tree, woody tissue is water-soaked and sponge-like. Removal of bark at the base of the tree will reveal the presence of what is known as mycellium, a light yellow, fan-like collection of fungal growth. Black, shoestring-like fungal growths may also exist amid the earth, while yellow or brown mushrooms called "basidiocarps" sprout from the ground, usually extending along the range of the tree's overhead canopy. If the disease has developed to this point, death is imminent.

Management

• The likelihood of a plum tree contracting this disease can be minimized if at least 20 years have passed since oaks or hickory were grown in the immediate area. However, once the disease is contracted, young plum trees may die within a year of suffering infection. If a tree is infected with oak root rot, the entire tree and its complete root system must be diligently removed from the area to prevent spreading the disease to other trees. All stone-fruit trees, including peaches, are susceptible.