PiCUS Sonic Tomograph

ArborMedics Offers Innovative Sonic Scanning of Tree Trunks

Arbormedics continues to be the only company in the Southeast to offer sonic scanning of tree trunks as a regular diagnostic service. This advanced diagnostic service allows us to literally see inside tree trunks using sound waves in a process similar to an ultrasound or MRI. The resulting scan image allows us to understand the structure and health of living trees in a new and dynamic way. The image also provides an accurate baseline for us to track the health and safety of trees over time. Sonic scanning uses the fact that the velocity of sound in wood depends on the modulus of elasticity and the density of the measured wood. Cavities, white rots, brown rots, and other fungal decay reduce elasticity and density in wood. These wood characteristics vary between trees species and between individual trees. The Picus Sonic Tomograph uses relative sound velocities so that the system calibrates itself automatically at each measured cross-section. The sonic scan provides information about the possible presence of decay and cavities within a tree. The system is not foolproof, however, and images should not be interpreted as fact. A tree should never be preserved, or removed, based solely on a sonic scan. A sonic scan is a test of one cross-section of the tree. The location of testing was chosen by your arborist based on visual signs of defect and limiting factors of the hardware. Please remember that the cross-section of the scan may not represent the weakest location in the tree’s overall structure. Fungal pathogens often invade the trunk via the buttress roots. It is safe to assume that if the scan identifies a potential fungal pathogen, it may have been active longer and more aggressively in the root system below the point of the scan.

Don't Drill Holes in Your Trees!

Unfortunately, the majority of arborists in the Southeast continue to use hand drills or "Resistograph" machines in an attempt to locate decay in tree trunks. These machines were developed to find rot in telephone poles---not living trees! When arborists drill into a living tree trunk, they breach the tree's natural defensive barriers and allow decay fungi to move from sick to healthy areas of the tree trunk. You will find an in-depth technical article about this problem in our .pdf download section entitled "Development of decay in the sapwood of trees wounded by the use of decay-detecting machines" by W. Kersten and F.W.M.R Schwarze.
Besides injuring the very tree it is trying to evaluate, a "resistograph" machine produces far less data than our sonic scans. A typical arborist would drill a tree 6-10 times in an tree inspection and have to guess the rest of the story. A typical sonic scan creates the equivalent amount of data as 189 drillings and provides that information in an accurate, digital image.


ArborMedics offers sonic scans at a lower rate than our competitors' invasive drilling procedures. It is our philosophy that sonic scanning should be affordable so that people can understand important issues about their tree's health and safety.