Fall is the time of year to look for fruiting bodies of rot fungi. Without being noticed, a fungus can be hard at work destroying a tree’s stabilizing structure. When the fungus finally sends out a spore-releasing reproductive body, it can be recognized and identified. After summer drought, trees are very stressed making them attractive to attack by rot fungi. It is possible for a tree with basal mushrooms to snap off at the root flare and fall. This is why it is important to closely monitor the trees on which rot fungi is seen. Knowing which trees are suffering from rot fungi will help to extinguish hazards before they occur.
The following are some trees in the Arboretum on which fungi has been noticed:

chestnut, willow, and red oaks at the top of the hill by Widener and the site of the old mansion are showing endothia canker fruiting bodies. This is a stress-induced fungus and usually is present in areas of old and new wounds. The small orange fruiting bodies appear at the root flare and on exposed roots that may have once been injured by mowing. Perhaps, these trees should have mulch rings around the bases to protect the protruding roots. The mulch would also contribute to soil improvement.

endothia canker

One of the two old white pines at the top of the magnolia slope (the one further from Widener) has several fruiting bodies of Globifomes laetporus sulfureus. These were bright yellow when they first appeared and have faded to reddish brown. Some are located at the base, out in the drip-line area, and on the main trunk in the canopy. Depending on how much rot has actually occurred, this tree could be in danger during storms with heavy winds, snow, or ice.

Globifomes laetporus sulfureus

The two old magnolias at the top of magnolia slope, which have been suffering from verticillium wilt for years, have several different kinds of rot fungi fruiting bodies on the branches and main trunks. Soon it will be time to remove these specimens.
The lace bark pine has developed small amounts of fruiting bodies at the root flare. All efforts should be made to keep the trunk safe from any type of damage.
The Fagus sylvatica at the corner of Hill Crest and Germantown ave. has some rot fungi mushrooms on old branch-cut scars. Otherwise, this tree is generally a healthy specimen for its age.
A Prunus sp. along the path that parallels Hill Crest is covered with a fungus called Trametes versicolor. The fruiting bodies are covering an old wound on the main leader and on some branches in the canopy. The tree seems to be surviving despite the large amount of fruiting bodies that have appeared.

Fairy ring of mushrooms

 

These mushrooms are an example of saprophytic fungi that live on dead or decaying matter (wood, humus, soil, grass, manure, and other debris). When there is an even distribution of nutrients in the environment, the mycelium (like a plant's roots) of a fungus may grow outward at the same rate underground. Periodically the fungus may produce mushrooms (a fungi's "fruit") on the outer fringes of the mycelium causing a ring or arc to form. These rings or arcs are called fairy rings, presumably because people used to think fairies danced in them. The photo above shows an example of a fairy ring arc growing in a lawn area.