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HomeMy WebLinkAboutTR_Arborist_Report_240818_v11 Alan Haywood Arborist & Horticulturist, LLC. Michael Ngo 1606 Kennewick Ave NE Renton, WA 98056 310-634-9396 July 29, 2024 Thank you for contacting me about your tree concern at your residence at 1606 Kennewick Ave NE in Renton, Washington. I am sending you this simple report as a follow up to the site visit I made on June 28, 2024, to look at the large Douglas fir (Pseudotsuga menziesii) tree in your backyard. You explained to me that you were the new owner of the property and that you were concerned about the tree, because it had a dead top. You asked me to assess the tree and determine if it was unhealthy or unsafe. You expressed that you would like to have it removed if it posed a threat to your house. When I arrived at your house, I found that the large Douglas fir and a fruiting cherry tree (Prunus avium) were the only two trees on the property. I examined the tree using the standard visual tree assessment method, as outlined in the Tree Risk Assessment Manual published by the International Society of Arboriculture. This is considered a Level 2 Basic Tree Risk Assessment. All of my observations were made at ground level. I did not climb the trees, excavate any soil, or perform any invasive tests. I used a Diameter tape to measure the diameter at breast height (DBH – taken at 4.5’ above ground level), binoculars to observe the upper crown of the tree and a rubber mallet to sound the tree’s trunk. The tree risk assessment methodology is based on three factors: - How likely is the tree, or part of the tree, to fail? - How likely is the tree, or tree part, to hit a target of value when it fails? - How likely is the tree, or tree part, to damage the target if it hits it? Tree risk is categorized as Low, Moderate, High or Extreme. A normal healthy tree is generally considered low risk, because it is not likely to fail. It is the presence of defects in the tree that increases the level of risk. Even normal, healthy, low risk trees can fail in extreme weather conditions. High risk trees are usually considered hazards and extreme risk trees are always hazards. The occupancy of the target is also factored into the risk rating. 2 I measured the tree and found it to be 40” DBH and 110’ tall, with a crown spread of 50’ and a Live Crown Ratio (LCR) of 70%. The top 15’ of the tree was dead. It appeared to have died fairly recently, as there were still dead needles (foliage) present. Dead needles usually persist on a tree for several months before falling off. There was also oozing pitch on the lower trunk and one side of the lower trunk had noticeable swelling. The back side of the trunk (facing away from the house) was kind of flat, as opposed to round. This indicates slower growth on that side of the tree. Based on this Level 2 Basic Tree Risk Assessment, I rate this as a High Risk tree. The top could break out during a high wind. It will become more likely to break out as time goes on as it dries out and becomes more brittle. If it lasts long enough, it will decay and get soft and easily break. This risk can be abated by pruning off the dead top, so removal isn’t warranted just because the top is dead. The question with this tree is, “Why did the top die?” Also, “Why is the trunk oozing pitch, why is its trunk swollen and why does its trunk have a flat side?” The dead top is obvious, but why did it die? The top may have died as a result of drought or a bark beetle infestation. Drought seems unlikely because the rest of the tree below the dead top looks fine, with no thinning of foliage. A dead top due to drought is possible, but the tree would usually have signs of stress throughout and this one doesn’t. Bark beetles are possible, but they usually attack lower on the trunk, where the trunk is thicker. A stem canker is also possible. Cytospora canker is known to occur on Douglas firs. If it was a canker, pruning the diseased portion off the tree is advised . This would keep the disease from spreading. The swelling of the trunk and the pitch oozing would not be related to a canker disease or from drought. Swelling can be caused by internal decay and the tree’s response to strengthen the trunk where it is weak. A flat side and slow growth on one side of a tree can be due to root stunting on that side of the tree. This can be from physical injury to the roots, competition from other trees on that side of the tree, poor soil on that side of the tree or a root disease. It would take an internal investigation of the tree to determine this. Pitch is a defense mechanism of the tree. It produces pitch when it has been injured. The pitch helps to prevent disease infection and insect infestation. There is usually some sort of wound associated with pitch. If nothing is visible on the outside of the trees, then the wound can be on the inside. Internal cracks in a tree can cause pitch production, as can old injuries with pockets of dead wood that have been callused over. A root disease, such as Armillaria, can cause pitching on a tree. It can also cause a flat side to develop. This would also take an internal investigation to determine. 3 The 40” DBH Douglas fir is classified as a Landmark tree by Renton City Code. Landmark trees can only be removed if: - They are determined to be a High Risk by an ISA Certified Arborist with the Tree Risk Assessment Qualification or, - If they are causing physical damage to buildings or infrastructure or, - If they block active solar collection devices or, - If they are in conflict with a City goal or purpose. The cherry tree was not carefully assessed, as it was not part of the assignment. I did note that the tree was healthy and bearing ripe cherries when I was there. You later measured the tree per my instructions and found it to be 19” DBH. My recommendation for this tree is as follows: 1. Propose removal of the tree due to its dead top and other features that may indicate a more serious problem. 2. If the City denies the removal proposal, have the tree climbed and the dead top removed, cutting it back to a live branch or branches. Have the dead top examined for cankers, bark beetles, etc. Continue to monitor the tree. If further dieback occurs, have the tree reassessed. Or, 3. Have a qualified arborist perform a Level 3 Tree Risk Assessment, where the lower trunk is examined and the roots on the flat side, to determine if there is any decay or disease present. This assessment is based on the information I gathered on the day of my site visit. I attest that all of the information within this report is accurate and true, to the best of my knowledge. It does not provide any guarantees or implications that the condition of the trees on this site won’t change over time. All trees eventually fail and even sound, healthy trees fa il during severe weather events, such as high winds, heavy rain or snow, or ice. A tree risk rating is usually considered valid for a one-year period, unless otherwise noted. Please feel free to contact me if you have any questions about this report or have further need of my services. Sincerely, Alan Haywood ISA Certified Arborist/Municipal Specialist – PN 0330-AM ISA Qualified Tree Risk Assessor ASCA Qualified Tree and Plant Appraiser WSNLA Certified Professional Horticulturist - 2332 ecoPRO Certified Sustainable Landscape Professional – 6017 WSDA Licensed Pesticide Consultant – 7627 PO Box 1086 Enumclaw, WA 98022 253-259-4474 alan@haywoodarborist.com 4