A tree health assessment is a systematic evaluation of a tree's condition by a qualified arborist, done to find out why a tree is struggling and what can be done about it. It is diagnosis, not guesswork. I look at the whole tree from the roots to the crown, along with the site around it, and deliver a written finding of what is wrong and a plan to address it. If you have a tree that is thinning, dropping leaves, growing mushrooms, or simply not looking right, this is the service that tells you what is actually going on.
Signs your tree needs a health assessment
A tree rarely fails all at once. It sends signals first, and the earlier they are read, the more options you have. Common warning signs include:
- Canopy dieback that starts at the top of the tree or the branch tips and works inward.
- Leaves that are undersized, off color, yellowing or browning out of season, or noticeably sparse.
- Premature leaf drop, or a canopy that leafs out late or unevenly in spring.
- Deadwood and dying branches scattered through an otherwise living crown.
- Dark bleeding, oozing, sunken cankers, or cracked and peeling bark on the trunk or limbs.
- Mushrooms or hard shelf conks at the base, on the roots, or on the trunk, which can point to internal decay or a root disease.
- A tree that has gone downhill quickly after nearby construction, grading, trenching, or a change in irrigation.
Most tree decline is about the site, not a bug
The most common mistake I see is reaching for a spray before anyone has asked why the tree is stressed. According to the University of California Statewide Integrated Pest Management Program, most disorders affecting landscape trees are abiotic, meaning they are caused by non living factors such as drought, overwatering, buried root collars, soil compaction, planting too deep, or mechanical injury, rather than by an insect or a disease. Those stresses come first, and the pests and pathogens follow. A drought stressed tree cannot close its wounds quickly, which is exactly when bark beetles and canker fungi move in. So a real health assessment starts with the growing conditions, then works up to the living pests, not the other way around.
What the assessment covers
I work from the ground up, because most serious tree problems begin below eye level:
- The site and soil: drainage, grade changes, recent construction, irrigation, and how much usable root space the tree actually has.
- The root collar and root zone: I check for a buried or girdling root collar, root disease such as Armillaria, and damage from trenching or compaction.
- The trunk and scaffold branches: cankers, bleeding, decay, cavities, cracks, and old wounds.
- The canopy: dieback pattern, foliage color and density, and shoot growth over recent seasons.
- Laboratory diagnosis when it is needed: for a fungal or pathogen question I identify the organism under the microscope rather than guessing from the outside, which is the part of this work I specialize in.
Tree health assessment or tree risk assessment?
These answer two different questions. A tree health assessment asks whether a tree is biologically healthy and what is making it decline. A tree risk assessment asks whether a tree is likely to fail and hit something, and how serious that would be. They overlap, because a sick tree is often a structurally weaker one, and I frequently do both on the same visit. But if your main concern is a limb over the house or a leaning trunk, start with the risk assessment. If it is a tree that looks unwell and you want it to recover, start here.
What you get
Every assessment includes a written report you can act on: the diagnosis, the evidence behind it, and a plant health care plan with clear next steps, whether that is a change in irrigation, soil or root collar work, targeted treatment, monitoring, or in some cases removal. A site assessment is $250 and includes that written report. Because I am an independent consulting arborist and do not run a removal crew, the plan is built around what is best for the tree and your property, not around selling you a cut.
University resources on tree health and diagnosis
- UC IPM: Landscape Tree Damage, It Is Not Always a Pest IssueUniversity of California guidance on why most landscape tree problems trace back to abiotic, non living causes rather than pests.
- UC IPM: Diagnosing the Causes of Unhealthy PlantsThe University of California framework for separating abiotic disorders from living pests and pathogens when a plant is in decline.
- ISA Arboriculture and Urban Forestry: The Diagnosis of Urban Tree DisordersA peer reviewed overview from the International Society of Arboriculture on the systematic diagnosis of tree disorders.
Frequently Asked Questions
What is a tree health assessment?
It is a systematic evaluation of a tree by a qualified arborist to find out why it is declining and what can be done. It covers the site, the roots, the trunk, and the canopy, and where needed it includes laboratory identification of a fungus or pathogen. The result is a written diagnosis and a care plan.
How much does a tree health assessment cost?
A site assessment is $250 and includes a written report with the diagnosis and a plant health care plan. If the situation calls for laboratory pathology or a more involved report, I will tell you the cost before any additional work.
How is it different from a tree risk assessment?
A health assessment asks whether the tree is biologically healthy and why it is struggling. A risk assessment asks how likely the tree is to fail and what it could hit. They overlap, and I often do both in one visit, but they answer different questions.
Can a stressed tree recover?
Often, yes, if the cause is caught early and corrected. A mildly stressed tree can decline within one or two growing seasons if it is ignored, but many trees rebound once the underlying problem, usually a site or water issue, is fixed. Some conditions, such as advanced root disease, cannot be reversed, and an honest assessment will tell you which case you are in.
What causes most tree decline?
Most of it is abiotic, meaning non living site stress: drought, overwatering, a buried root collar, compacted soil, or root damage from construction. Insects and diseases are often secondary, moving in after the tree is already weakened. That is why a good assessment starts with the growing conditions.