Through the process of Visual Tree Assessment (VTA) the assessing arborist may suspect there to be hidden internal defects within a tree. We employ modern diagnostic tools to investigate to accurately determine the presence and extent of decay.

We also carry out sub-level investigations to examine root disorders or to investigate possible root / construction conflicts.

Some of the techniques and tools we employ are:

    Ret trenching to determine the extent of root presence.

  • Root Exploratory Trenching
    Root Exploratory Trenching (RET) is a technique used to evaluate the extent to which a tree’s roots have colonized a given area of soil. Through this technique we can assess whether a proposed construction is tolerable from the point of tree health.
    Even when large ‘scaffold roots’ are found through RET we can often propose small design changes to overcome these constraints.

    The Resi drill in action

  • IML RESI System
    The RESI drill is based on the gentle measurement of drilling resistance. A drilling needle (1.5 – 3.0mm) is inserted into the wood under constant drive. While drilling, the resistance is measured as a function of the drilling depth of the needle. The measurement data is printed simultaneously on a paper strip and recorded electronically on a laptop computer. The measurement profile delivers information about the internal condition of the wood. It shows annual rings and density behavior as well as decayed zones within the wood. The information gathered using the RESI drill is then analyzed by our arborists to determine the extent of decay and its effect on the trees structure. 

    The Picus Sonic Tomograph measures the speed at which a sonic pulse travels through a tree from various points (based on the principle that sound travels faster through good wood than decayed wood). The sonic pulse is generated by contact with pins with a digital hammer, around the tree’s circumference. Sensors, attached to the pins, measure the time sound takes to travel through the wood. Once all the pins have been tapped, the information is sent to a laptop where the speed variations are displayed using a range of colours to accurately map the shape and internal density of the tree. The sample image below illustrates this: 

    Brown indicates sound wood with significant strength. Purple, Blue and White indicate decayed wood or possible hollows. Green indicates transitional wood.

The Picus at work

These systems are an essential tool in modern arboricultural consultancy.
Through the use of the PICUS and RESI systems, trees which may otherwise be condemned using other assessment methods are able to be more accurately assessed for decay and in many cases the risk is able to be managed for years to come.