A

Air spade
A high-pressure compressed-air tool that removes soil from around tree roots without cutting them. Used for root collar excavation, locating girdling roots, and finding utilities safely near trees.
Anthracnose
A fungal leaf and twig disease affecting sycamores, ash, oaks, and maples. Causes irregular brown blotches on leaves, usually after wet springs. Most often cosmetic on mature trees.
ANSI A300
The American National Standards Institute pruning standard. Defines proper pruning cuts, what's acceptable, and what's not. Professional arborists prune to this standard.
Arborist
A trained professional who specializes in the care of individual trees. An ISA Certified Arborist has passed a 200-question exam and maintains continuing education credits.

B

Bacterial Leaf Scorch (BLS)
A disease caused by Xylella fastidiosa bacteria that clog a tree's water-conducting xylem. Common on DFW red oaks and live oaks. Marginal leaf browning with a yellow halo. Treatable with oxytetracycline injection.
Branch collar
The slight swelling where a branch meets the trunk. Pruning cuts should be made just outside the collar — never flush with the trunk and never far from it.
BBB Accredited
A business accredited by the Better Business Bureau, meeting their standards for trust, transparency, and complaint resolution.

C

Cabling
Installation of steel cables in a tree to support weak limbs or co-dominant stems. Reduces failure risk without removing the tree. ANSI A300 Part 3 governs installation.
Canopy
The upper part of a tree formed by its branches and leaves.
Certified Arborist
A tree care professional credentialed by the International Society of Arboriculture (ISA). Requires passing the certification exam and maintaining CEUs.
Chlorosis
Yellowing of leaves caused by lack of chlorophyll. In DFW most commonly caused by iron deficiency from alkaline soils locking up the iron in the dirt.
Co-dominant stems
Two main trunks of nearly equal size growing from a single point. Often have weak "V" attachments that can split in storms. Cabling can reduce risk.
Crown
Synonym for canopy — the leafy part of a tree above the trunk.
Crown raising
Removing lower branches to provide clearance for buildings, vehicles, sidewalks, or sightlines.
Crown reduction
Carefully reducing the size of a tree's canopy by cutting back to appropriate lateral branches — NOT to be confused with topping.
Crown thinning
Selective removal of branches to reduce density, improve light penetration, and reduce wind load. Done properly, leaves no visible "holes."

D

DBH (Diameter at Breast Height)
The standard measurement of tree trunk diameter, taken at 4.5 feet above ground. Used for pricing and assessment.
Deadwooding
Removal of dead branches from a tree. The single most important safety pruning task.
Deep root fertilization
Injection of liquid nutrient solution directly into the root zone using a soil probe. Far more effective for urban trees than surface fertilizing.
Defoliation
The loss of leaves, usually from insect damage, disease, or environmental stress.
Drip line
The outer edge of a tree's canopy where water naturally drips off the leaves to the ground. Feeder roots typically extend to and beyond the drip line.
Dutch Elm Disease
A fungal vascular disease spread by beetles that wilts and kills American elms. Preventable with periodic propiconazole injections.

E

Emerald Ash Borer (EAB)
An invasive beetle that kills ash trees. Approaching North Texas. Preventable on valuable ash with trunk injection of imidacloprid or emamectin benzoate.
Excavation (root collar)
Removing soil from around the base of a tree to expose the root flare. Often reveals girdling roots or buried trunks killing the tree.

F

Feeder roots
The fine roots that absorb water and nutrients. Typically found in the top 12–18 inches of soil, extending out to and beyond the drip line.
Fire Blight
A bacterial disease (Erwinia amylovora) that scorches blossoms and shoots on pears, apples, and other rose-family trees. Treated with sanitation pruning and timely sprays.
Flush cut
A pruning cut made flat against the trunk, removing the branch collar. Considered improper because it prevents the tree from sealing the wound and invites decay.

G

Ganoderma
A genus of wood-decay fungi that cause root and butt rot. Visible "conks" on the trunk often mean major internal decay.
Girdling root
A root that grows in a circle around the trunk instead of outward, eventually strangling the tree as both grow. A major hidden cause of urban tree decline.

H

Hardpan
A compacted soil layer that resists water penetration and root growth. Common in DFW clay soils, especially after construction. Treatable with aeration.
Hazard tree
A tree with a structural defect or condition that poses a meaningful risk of failure. Assessed using the TRAQ framework.
Hypoxylon canker
An opportunistic fungus that attacks drought-weakened oaks. Often a sign the tree is already in major decline.

I

Iron chlorosis
Yellow leaves with green veins caused by iron deficiency. In DFW, the most common tree problem — caused by alkaline clay soil chemically locking up iron. Treatable with trunk injection.
ISA
International Society of Arboriculture, the credentialing body for arborists. ISA Certified Arborist is the gold-standard credential.

L

Lion-tailing
Improper pruning that strips interior branches and leaves only foliage at the tips. Looks tidy but biomechanically catastrophic — wind load concentrates at the tips and major limbs fail.

M

Macro-infusion
A trunk injection method that delivers larger volumes of treatment (fungicide, antibacterial) into a tree's vascular system. Used for oak wilt and BLS.
Micro-injection
Trunk injection that delivers smaller volumes — used for chlorosis, EAB prevention, and similar applications.
Mulch volcano
Mulch piled in a cone against the trunk of a tree. Slowly kills the bark by suffocation and trapping moisture. Mulch should be in a flat ring, not against the trunk.

O

Oak wilt
The most aggressive tree disease in Texas, caused by Ceratocystis fagacearum. Spreads root-to-root and by beetles. Treatable with macro-infusion of propiconazole if caught early.

P

Phytophthora
A genus of water mold that causes root rot. Kills feeder roots, causing leaves to wilt even with adequate watering.
Plant Health Care (PHC)
A proactive annual program for trees and shrubs — feeding, treating, scouting, repeating. The way valued landscapes are maintained.
Pruning
The selective removal of branches to improve a tree's structure, health, appearance, or safety. Done properly, follows ANSI A300.

R

Root collar (or root flare)
The widening at the base of a trunk where the trunk transitions into roots. Should always be visible at grade level — burial under soil or mulch suffocates the tree.

S

Sap-feeding beetles
Insects (nitidulids) that vector oak wilt during the Feb–June risk window. Reason oak pruning must be sealed in this window.
Sealant (wound dressing)
Material applied to a pruning cut. For most species, NOT recommended (slows healing). For oaks during oak-wilt season in Texas, absolutely required.
Sucker
A vigorous shoot growing from the base, roots, or trunk of a tree. Usually a stress response.

T

TCIA
Tree Care Industry Association, the safety and professionalism standards body for tree services. Members are accredited and inspected.
TDA License
Texas Department of Agriculture pesticide applicator license — required by state law for commercial chemical applications on trees.
Topping
Cutting major branches back to stubs to reduce tree height. Destructive — shortens tree life, creates dangerous water sprouts, considered malpractice in modern arboriculture.
TPDDL
Texas Plant Disease Diagnostic Laboratory at Texas A&M — the lab certified arborists use to confirm tree disease diagnoses.
TRAQ
Tree Risk Assessment Qualification — the standardized framework for evaluating tree-failure hazards. Used in insurance, legal, and HOA reports.

V

Vascular system
A tree's network of xylem (water transport) and phloem (sugar transport) tissue. Many tree diseases attack this system — that's why systemic injection treatments work.
Vertical mulching
Drilling holes around a tree's drip line and filling with composted material to relieve soil compaction without cutting roots.

W

Water sprouts
Vigorous, weakly-attached shoots that grow from major branches, often after topping. Look unnatural and fail in storms.
Widow-maker
A broken or hanging limb caught in a tree's canopy that could fall at any time. Common after storms. Always assume they're dangerous.

X

Xylem
The water-conducting tissue in the trunk and branches of a tree. Many vascular diseases (oak wilt, BLS, Dutch elm) attack the xylem directly.