On Saturday February 8th TreePro was contacted to help one of our clients in Bodega Bay who had experienced a major limb failure that landed on their garage. After a Pre-Job Safety Inspection we went to work to remove the limb so we could cover the garage with a tarp to protect the client's possessions.
A neighbor reported that the wind had been howling in the night and he heard a rumble when the tree section fell. This was one of three emergency jobs we were called over the stormy weekend.
This tree failure occurred where two trunks were joined. Co-dominant trunks or leaders that have a high "V" shaped attachments have a condition known as"included bark." When the bark is included the tree is unable to grow tissue between the trunks. This can lead to splits at the crotch where the limbs or trunks meet. Branches with horizontal attachments have better attachments and are less likely to fail. However, when horizontal limbs become greater than half the diameter of the tree's trunk they are also subject to greater stress and have a higher risk of failure.
When branches are wet from the rain they become heavier and this added weight combined with wind create the potential for limb failures.
When trees fall over at the base and the roots are pulled up there are several factors that contribute to this type of failure. A large tree with a heavy canopy has a lot of "wind sail" which
catches the wind much like the sail on sail boat. The roots of the tree may be compromised by root fungi that cause die back of the large roots that provide support for the tree. Some common root fungi that affect our native trees include phytopthera and armallaria mallea. These are the most common fungi that affect native oaks.
When soils become saturated in combination with strong winds, trees are more likely to fail at the root crown.
Often it is difficult to determine if root fungi are affecting a tree in the home landscape. Trees may look healthy but at the same time be compromised by a root system that has decay and root loss. There are some clues that may indicate problems in the root system. Mushrooms growing near the base of the tree may be an indicator of armallaria mallea pathogen. Hypoxylon is an indicator of dead tissue at the trunk of the tree. It is identified as black rounded knobs about the size of a quarter. If a tree has dieback of the branch tips or areas in the upper canopy that are dead it may mean the root system is in trouble. Another problem area is cavities in the trunk or branches. Holes in the trunk indicate an area of decay and a potential area for tree failure.
Another common fungi in our area is Ganoderma Appalatum which is a growth that occurs at the lower trunks of tree with decay. This fungi is flat shaped growth with a brown top and a white bottom that grows out of the tree trunk.
It is a good idea to have your mature trees inspected on a yearly basis by a Certified Arborist to identify potential hazards and provide recommendations to mitigate those hazards. The mitigation may include reducing weight on heavy limbs or limbs with weak attachments. In some cases it is advisable to install cables or braces to add support to tree limbs or trunks.
Trees add value and beauty to your home. Inspections and regular maintenance will help to promote tree health and reduce hazards.
Ron Wallace, Certified Arborist #WE 0979A