By itself, tree decay can be a major concern, especially if found in a soft-wooded tree species such as silver maple or poplar. Fortunately, some species are quite resistant and if other stressors aren’t present in a significant capacity, it may not be as worrisome as other problems such as poor location, planting errors, overfertilization or drought. A step-by-step approach works best when inspecting trees for decay:

  1. Use your eyes. Look for rot pockets, oozing, weeping, conks and different colors on the bark and branches.
  2. Walk the property extensively and identify possible targets. Interview the property owner and neighbors to get a handle on the frequency of use on the site.
  3. Use your experience. Certain tree species in certain locations are likely to develop decay. Locate tree parts that could fall on a target.
  4. Look closer using probing tools: golf club, rebar or irrigation flag. Use a rubber mallet or the butt of a hatchet to tap the tree trunk where you suspect decay is present.
  5. If necessary, use invasive tools such as a resistograph or core sampler. Reserve these for important tree specimens. For example, inspecting an oak at the entrance to the “Harvard Oaks” subdivision or a memorial tree. If the property owner has plenty of money to spend on inspection, consider the use of a sonic tomograph, a device that can illustrate the inside of the tree without cutting into it.
  6. Consider the potential for each tree defect to cause failure in conjunction with the proximity of an important target.
  7. Put it all together in the form of a relative hazard assessment, combining the presence and extent of the decay with other defects.

Editor’s note: These steps were taken from an article by John Fech in the November 2012 issue of Tree Services.