Tree Killing Fungus

Fungi can appear like brackets on a tree trunk.

There are a number of fungi that can kill a tree. Often called heart or sap rot, the fungi enters the tree and begins to reduce its strength. There are few trees that are not susceptible to trunk or limb decay.

Types of Fungus

From colorfully named artist's conk to turkey tail, there are many fungi types that can get inside a tree and cause enough damage and decay to kill the tree. Ash, birch, willow, chestnut and elm trees seem to be the most often afflicted by fungi. Fungus usually forms at the base of trees following heavy rains or finds crevices formed by broken limbs. Sulfur fungus, oyster mushroom, common split gill, parchment fungus and varnish fungus rot can all harm or kill a tree.

Identification

Look for the conks, brackets or other fungi structures near "wounds in bark, at branch scars, or around the root crown," advises University of California Davis Extension. White rot breaks down the lignin and cellulose, causing the wood to feel spongy and look white or yellow. Brown rot destroys the cellulose and leaves behind the brown lignin and wood that crumbles. Soft rots involve both bacteria and fungi. They work more slowly and only in very localized areas, so they rarely kill trees.

Management

Once a fungus starts to thoroughly invade a tree, it is difficult to treat. Healthy trees that are pruned and cared for properly are rarely invaded by fungus. Cut and remove diseased limbs or branches. Make cuts so rainwater will drain. Wound dressings should not be used because they can encourage bacterial and fungal growth. Trees already severely affected by fungus may have to be removed all together.

References

• University of California Davis Integrated Pest Managment: Wood Decay Fungi in Landscape Trees
• Virginia Cooperative Extension: Anthracnose - A Fungal Disease of Shade Trees