Improving Hazard Tree Diagnostic Tools for Arborists: How Well do Visual Observations of Fungal Fruiting Bodies Predict Extend of Wood Decay in Urban Trees?

2007 | Jason A. Smith, University of Florida

Preventing tree failure due to fungal decay can save millions of dollars and many lives each year. This prevention must be balanced with many other issues including aesthetics, removal costs, jurisdictional issues, legal issues and public attitudes. Thus, prevention strategies must rely on the most efficient and accurate methods of assessment to insure success.  Current methods range from high tech and non-destructive such as magnetic resonance imaging (MRI) to simple, such as visual observations of decay and fungal fruiting bodies and destructive sampling (e.g. drilling). The high tech methods require much less destructive sampling, but require expensive equipment and user expertise.  Therefore, utilization of rapid, cost-effective standard protocols for assessment of hazard trees is a primary need for arborists nationwide.  One of the most utilized approaches to assessment of decay has been visual inspection for fungal fruiting bodies (a.k.a. “conks”) produced primarily by Basidiomycete fungi. Although it is a long held belief in the arboricultural industry that the presence of fungal fruiting bodies indicates the presence of extensive decay, there have been no systematic surveys done to validate this.  In addition, very little is known about species-specific risks associated with the presence of specific fruiting bodies. Preliminary surveys conducted in Florida indicate that although certain conks may be present, little to no decay is found. Arborists in the state of Florida and elsewhere are requesting better information about conk presence and extent of decay. By collaborating with a network of arborists in the field in Florida, this project will determine how presence and types of fungal fruiting bodies relate to the extent of wood decay present in urban trees. In addition, we will classify and quantify decay types present in surveys (depending on stem diameter and distance from fungal fruiting bodies) and use this data to establish recommendations for arborists to follow that will guide decision-making when assessing hazard trees in the field. This is the first project of its kind in North America.

For more information on this project, contact the researcher via TREE Fund at