Sometimes, a tree can develop issues that compromise its stability and strength. These problems may manifest visually, such as the presence of a cavity or fungus at the base, or they might become apparent when tapping the trunk or root flares (the parts of the root emerging above ground) and detecting a hollow sound. To ascertain whether a tree is at risk of failure, which could involve it falling over or breaking at a weak point, it's crucial to determine the presence and extent of decay. The Resistograph® machine plays a pivotal role in addressing these critical questions.
Resistograph testing does come with added inspection costs. However, we don't undertake it unless our arborist has a valid reason to do so. Our goal is not to inflate your bill but to ensure the structural integrity of your tree. When the Resistograph reveals significant decay within a tree, it can potentially save homeowners thousands of dollars in structural repairs and even safeguard lives by signalling that the tree requires removal.
The Resistograph® employs a stainless-steel drill bit measuring 1/16 inch in diameter and approximately 50 centimetres in length. As the machine's gear drives the drill bit into the tree, the wood's resistance is recorded on a paper strip or displayed on the machine's computer screen, resembling an EKG. Through analysis of the results, our arborist can determine whether the tree is hollow, decayed, or structurally sound. A flat line indicates minimal resistance to the drill, signifying a hollow or decayed area, while a jagged line reflects resistance and the presence of sturdy wood.
Drilling a tree with a Resistograph is considered minimally invasive, causing no long-term harm. The small-diameter drill bit leaves a hole that the tree can naturally seal over the course of a few years' growth.
Typically, we perform drilling in common areas, including the lower part of the trunk and the points where roots extend from the trunk, known as root flares. If the tree exhibits a lean, we initiate drilling beneath and opposite the lean, addressing the two primary tension points of the tree. Additional drillings may be necessary based on factors such as the nature of the problem, the tree's size, and the findings from the initial drills. Occasionally, we may also need to drill at the junction where a large branch meets the trunk higher up in the tree if there are suspicions of decay, such as the presence of a cavity, visible mushrooms, or signs of wildlife activity like cockatoos frequenting the tree.
