Tree Care
Glossary
The definitive dictionary of professional arboriculture terminology for homeowners, estate managers, commercial property managers, and municipalities in Southern California.
ANSI A300
ADefinition
The generally accepted industry standards for tree care practices in the United States, developed by the Tree Care Industry Association (TCIA).
Why It Matters
Following ANSI A300 standards ensures that pruning and other tree care activities promote tree health rather than causing irreversible damage.
When You'll Encounter It
Homeowners will see this referenced in professional proposals and contracts to guarantee quality work.
When to Call an Arborist
When hiring any tree care company, ask if they strictly follow ANSI A300 pruning standards.
Air Spading
ADefinition
A technique that uses compressed air to safely excavate soil around a tree's root zone without damaging the delicate roots.
Why It Matters
It allows arborists to diagnose root issues, relieve soil compaction, and safely install utilities near valuable trees.
When You'll Encounter It
When a tree shows signs of decline due to compacted soil or root collar burial.
When to Call an Arborist
If your tree looks sick and the base of the trunk looks like a telephone pole going straight into the ground.
Anthracnose
ADefinition
A group of fungal diseases that cause dark, sunken lesions on leaves, stems, flowers, and fruits.
Why It Matters
Repeated defoliation from anthracnose can weaken trees, especially Sycamores and Oaks, making them susceptible to other pests.
When You'll Encounter It
During cool, wet springs when leaves emerge with brown patches or drop prematurely.
When to Call an Arborist
When you notice widespread leaf spotting or early leaf drop in the spring.
Bark Beetles
BDefinition
Small insects that bore through the bark of trees to lay eggs, disrupting the flow of water and nutrients.
Why It Matters
Bark beetles can rapidly kill mature, drought-stressed trees, especially pines in Southern California.
When You'll Encounter It
When trees are stressed by drought or when you notice small holes in the bark with pitch tubes (sap dripping).
When to Call an Arborist
Immediately if you see sap oozing from small holes in the trunk of your pine or oak trees.
Basal Flare
BDefinition
The rapid thickening of the trunk at the base where it transitions into the root system.
Why It Matters
The basal flare must be exposed to the air. If buried by soil or mulch, the bark can rot, leading to tree death.
When You'll Encounter It
During landscaping projects or when mulch is improperly piled against the trunk (mulch volcanoes).
When to Call an Arborist
If your tree's trunk goes straight into the ground without a visible flare at the base.
Cambium
CDefinition
A thin layer of living, actively dividing cells just under the bark that produces new wood and bark.
Why It Matters
It is the lifeline of the tree. If the cambium is severed completely around the trunk (girdling), the tree will die.
When You'll Encounter It
When trees are damaged by weed whackers, lawnmowers, or construction equipment.
When to Call an Arborist
If the bark of your tree has been significantly damaged or stripped away.
Canopy
CDefinition
The upper layer of a tree formed by its branches and leaves.
Why It Matters
The canopy produces the tree's food through photosynthesis and provides shade, cooling the surrounding environment.
When You'll Encounter It
When discussing pruning, shade potential, or assessing the overall health of the tree (e.g., a thinning canopy).
When to Call an Arborist
If the canopy looks unusually thin, has dead branches, or is growing too close to structures.
Certified Arborist
CDefinition
A professional who has achieved a level of knowledge in the art and science of tree care through experience and by passing a comprehensive examination developed by some of the nation's leading experts on tree care.
Why It Matters
Ensures the person advising on or working on your trees understands tree biology and proper care techniques.
When You'll Encounter It
When searching for qualified tree care professionals to assess or treat valuable landscape trees.
When to Call an Arborist
Whenever you need a diagnosis, a long-term care plan, or high-quality pruning for your trees.
Deep Root Fertilization
DDefinition
A process where specialized liquid nutrients are injected directly into the root zone of a tree under pressure.
Why It Matters
It bypasses competing turf roots, alleviates soil compaction, and delivers nutrients exactly where the tree can absorb them.
When You'll Encounter It
When trees are showing signs of nutrient deficiency, slow growth, or recovering from stress.
When to Call an Arborist
In the spring or fall to boost tree health, or if your tree's leaves are yellowing.
Defensible Space
DDefinition
The buffer you create between a building on your property and the grass, trees, shrubs, or any wildland area that surround it.
Why It Matters
Critical for slowing or stopping the spread of wildfire and protecting your home in Southern California.
When You'll Encounter It
When preparing for fire season or complying with local fire department brush clearance regulations.
When to Call an Arborist
Before fire season begins to ensure your trees are properly pruned and spaced.
Epicormic Growth
EDefinition
Rapidly growing shoots that emerge from dormant buds under the bark, often in response to severe stress or over-pruning.
Why It Matters
These shoots (often called water sprouts) are weakly attached and indicate that the tree is stressed and trying to quickly replace lost foliage.
When You'll Encounter It
After a tree has been 'topped' or severely pruned, or when it is suffering from root damage.
When to Call an Arborist
If your tree suddenly sprouts many small, fast-growing branches from the main trunk or large branches.
Girdling Roots
GDefinition
Roots that grow in a circular pattern around the trunk or other roots, eventually choking off the flow of water and nutrients.
Why It Matters
If left untreated, girdling roots will slowly strangle and kill the tree.
When You'll Encounter It
Often caused by trees being grown in pots too long before planting or planting a tree too deeply.
When to Call an Arborist
If your tree has a flat side at the base of the trunk or you can see roots wrapping around the trunk.
Plant Health Care (PHC)
PDefinition
A holistic, comprehensive program to manage the health, structure, and appearance of plants in the landscape.
Why It Matters
Focuses on preventing problems through proactive monitoring, proper nutrition, and soil health rather than just reacting to pests.
When You'll Encounter It
When looking for long-term management of luxury estates, HOAs, or valuable landscape trees.
When to Call an Arborist
When you want to protect your landscape investment and keep your trees healthy year-round.
Pruning
PDefinition
The selective removal of plant parts to meet specific goals and objectives, such as safety, health, or aesthetics.
Why It Matters
Proper pruning improves tree structure and reduces the risk of failure, while improper pruning (like topping) can permanently damage or kill a tree.
When You'll Encounter It
During routine landscape maintenance or when branches interfere with structures or power lines.
When to Call an Arborist
When a tree's branches are dead, crossing, or growing too close to your home.
Risk Assessment
RDefinition
A systematic process used to identify, analyze, and evaluate tree risk.
Why It Matters
Helps property owners make informed decisions about whether to preserve, mitigate, or remove a potentially hazardous tree.
When You'll Encounter It
When a tree has a visible defect, leans heavily, or after a severe storm.
When to Call an Arborist
If you are concerned that a large tree might fail and damage property or injure someone.
Root Zone
RDefinition
The area of soil where a tree's roots are actively growing and absorbing water and nutrients, often extending far beyond the canopy's edge.
Why It Matters
Protecting this area from compaction, construction, and chemical damage is vital for the tree's survival.
When You'll Encounter It
During construction projects, landscaping changes, or drought periods.
When to Call an Arborist
Before starting any construction, trenching, or major landscaping near mature trees.
Soil Testing
SDefinition
The process of analyzing soil samples to determine nutrient content, pH level, and composition.
Why It Matters
Provides the exact data needed to create a custom fertilization plan rather than guessing what a tree needs.
When You'll Encounter It
When trees are yellowing, failing to thrive, or before planting new high-value trees.
When to Call an Arborist
If your trees show signs of decline despite adequate watering.
Structural Pruning
SDefinition
Pruning designed to improve tree architecture, typically by establishing a dominant leader and removing weak branch attachments.
Why It Matters
Prevents future branch failures by training the tree to grow strong and stable from a young age.
When You'll Encounter It
Usually performed on young to medium-aged trees to establish a strong framework.
When to Call an Arborist
Every 2-3 years while a tree is young to ensure it grows safely.
Tree Injection
TDefinition
A method of delivering pesticides, fungicides, or fertilizers directly into the vascular system of a tree.
Why It Matters
It is highly targeted, environmentally safe (no spraying), and works quickly since it enters the tree's sap stream.
When You'll Encounter It
When treating for pests like the Shot Hole Borer or diseases that cannot be managed topically.
When to Call an Arborist
When your arborist recommends a targeted treatment for severe insect or disease issues.
Wood Decay
WDefinition
The deterioration of wood tissue caused by fungi or bacteria, which compromises the structural integrity of the tree.
Why It Matters
Extensive decay can lead to sudden, catastrophic tree failure, especially during high winds.
When You'll Encounter It
When you see mushrooms growing on the trunk, large cavities, or hollow sounding wood.
When to Call an Arborist
Immediately if you see fungal fruiting bodies (mushrooms/conks) attached to the trunk or roots.