Cracks on the trunks of trees may be caused by environmental factors such wind, harsh winter conditions and mechanical injuries among others. Cracks become the entrance point for decay fungi. Fungi are well-known recyclers, as they possess the enzymatic machinery to degrade a wide variety of compounds present in the wood.
As fungi develop and extract nourishment from the wood components, fungi produce mushrooms (fungal bodies visible with the naked eye that bears spores). Mushrooms are often referred as conks given their shapes. Moisture, provided by bountiful spring rains we have experienced, is a key factor for fungi to thrive and mushrooms start to pop up.
There are two main categories of wood rot caused by fungi: brown rots and white rots. White rot is much more widespread in nature. Several fungal species cause white rot, a type of wood decay were the fungi are capable of degrading all wood component including lignin. During the white rot process, the wood maintains it fibrous nature but gradually losses strength. On the other hand, brown rot decay occurs faster in comparison with white rot.
What both rot types have in common is that once they have started in the wood there is no cure or treatment proven to eradicate it from the tree. Whenever we receive pictures and samples of a tree that has a mushroom conk, the concern is the potential of internal decay. We at the clinic recommend having the tree evaluated by a trained arborist to determine it still maintains its structural integrity.
Trees with mushrooms or conks may pose a hazard to your property or people if the tree fails and falls. A trained arborist can help determine the branch and tree structural integrity and if it poses a hazard to your property or people if the tree fails and falls. For information on how to choose and arborist visit the resource Choosing-an-Arborist on the ISU Extension Store.
For information on brown and white rot visit this site and the Horticulture and Home Pest Newsletter from July 11, 2007.