I See a Hole in My Tree, Now What?
Written by: Consulting Department Manager, TRAQ, Nathan Schuettpelz
Trees in urban landscapes live in hostile environments. Extreme weather, a variety of pests, and physical damage are all factors that can impact the health of urban trees and can result in decay. Tree decay is dead tree tissue. Decay can be internal or external, spreading or contained, each of which can be determined to be high risk or low risk. When we see or detect decay in an urban tree, there are multiple factors to consider when determining how much is too much.
Trees cannot heal their wounds. The primary defense a tree has against decay is to seal off the wound and outgrow the threat. The tree tissue that seals off decay is referred to as “wound wood”. Tree tissue that then grows over the wound and decay is “response wood”. Tree species respond differently to wounds and decay. Oak trees are very good at sealing decay and the response wood is very strong. Soft-maple species like silver maple do not seal decay well. They may be able to grow rapidly to seal off a wound, but in that time the decay spreads rapidly causing a lot of harm.
Arborists are trained with techniques and tools to assess the presence and extent of decay. We will “sound” a tree listening for internal cavities. We then use tools that determine the location and extent of decay. If there is a small, isolated pocket of decay surrounded by good living tissue, we may say everything is fine. If we can see an open cavity and then measure a significant amount of spreading decay, we might recommend removal.
When assessing tree decay, observations of the surrounding site are just as important as assessing the tree itself. Using my tree risk assessment training, when I am in the field assessing tree decay, I am focusing on the surrounding site as much as I am looking at the tree. Extensive decay in a tree that leans over a house will have greater implications than decay in a tree located in an open park-like landscape. I might recommend removal of a tree that could demolish a home, whereas I might recommend restricting traffic to the immediate area surrounding a tree in a yard since the likelihood of damaging something is minimized due to its location.
Too summarize, there are no hard and fast rules when it comes to assessing tree decay. We acknowledge that tree decay happens. Trees have defense mechanisms to overcome decay, but sometimes the damage is too great. The Certified Arborists at Wachtel Tree Science are trained professionals that understand trees. Call us today to get the answers you need to understand your trees.