ISA ARBORIST PRACTICE EXAM 2025/2026 QUESTIONS
WITH ANSWERS GRADED A+
✔✔aggregate - ✔✔(1) close cluster of mix of small particles of soil and/or organic matter
of varying sizes that are bonded together; sand, gravel, or small rocks in soil; and/or
sand, gravel, or small rocks used under paved surfaces. (2) clusters of flowers or fruits
that appear as a single unit. (3) individual tree crowns that form a canopy.
✔✔Air excavation device, air excavator - ✔✔device that directs a jet of highly
compressed air to excavate soil. Used within the root zone of trees to avoid or minimize
damage to the roots, or near underground structures such as pipes and wires to avoid
or minimize damage to them.
✔✔air terminal - ✔✔uppermost point of a tree lightning protection system.
✔✔aircraft cable - ✔✔steel wire rope of various constructions designated by the number
of strands in the rope and the number of wires in each strand. Commonly used in
cabling in Australia and New Zealand.
✔✔allelochemical - ✔✔substance produced naturally by plants as part of a defense
against pests and other plants. May adversely affect the growth and development of
other plants.
✔✔allelopathy - ✔✔chemical effect or inhibition of growth or development of plants that
is induced by allelochemicals
✔✔alternate - ✔✔pertaining to bud or leaf arrangement, one leaf or bud at each node,
situated at alternating positions along the stem. In this arrangement, the leaves are not
directly across from each other. Contrast with opposite and whorled.
✔✔amon-eye nut - ✔✔specialized nut used in cabling trees that has a large eye for
attaching a cable to a threaded rod.
✔✔anaerobic - ✔✔without oxygen. Process that occurs in the absence of oxygen.
✔✔anchor hardware - ✔✔hardware to which the cable termination is affixed in a cabling
or guying installation.
✔✔angiosperm - ✔✔plant with seeds borne in an ovary. Consists of two large groups:
monocotyledons (grasses, palms and related plants) and dicotyledons (most woody
trees, shrubs, herbaceous plants, and related plants). Contrast with gymnosperm.
✔✔anion - ✔✔ion that carries a negative charge. Contrast with cation.
,✔✔ANSI A300 - ✔✔In the United States, industry-developed, national consensus
standards of practice for tree care.
✔✔ANSI Z133.1 - ✔✔In the United States, industry developed, national consensus
safety standards of practice for tree care.
✔✔anthocyanin - ✔✔red or purple pigment responsible for those colors in some parts of
trees and other plants. Compare to carotenoid.
✔✔antigibberellin - ✔✔plant growth regulator that inhibits the action of the plant
hormone gibberellin, which, among other things, regulates cell elongation.
✔✔antitranspirant - ✔✔substance applied to the foliage of plants to reduce water loss
(transpiration).
✔✔apical bud - ✔✔bud at the tip of a twig or shoot.
✔✔apical control - ✔✔inhibition of lateral buds, decreasing from the top down, by apical
buds over many seasons, resulting in trees with an excurrent growth form.
✔✔apical dominance - ✔✔condition in which the terminal bud inhibits the growth and
development of the lateral buds on the same stem formed during the same season.
✔✔apical meristem - ✔✔growing point at the tips of shoots and roots.
✔✔apoplasm - ✔✔free spaces in plant tissue. Includes cell walls and intracellular
spaces. Contrast with symplasm.
✔✔appropriate response process (ARP) - ✔✔method of systematically assessing plant
health and client needs to determine which course of action, if any, is recommended.
✔✔approved - ✔✔in the context of guidelines, standards, and specifications, that which
is acceptable to federal, state, provincial, or local enforcement authorities or is an
accepted industry practice.
✔✔arboriculture - ✔✔practice and study of the care of trees and other woody plants in
the landscape.
✔✔arborist block - ✔✔heavy-duty pulley with an integrated connection point (bushing
for attaching a rope sling), a rotating sheave for the rope, and extended cheek plates.
Used in tree rigging operations.
✔✔ascender - ✔✔piece of gear that enables a climber to ascend a rope. Attached to
the rope, it will grip in one direction (down) and slide in the other (up).
,✔✔augmentation - ✔✔in Plant Health Care, the release of beneficial organisms to
suppress pest insect or mite populations.
✔✔auxin - ✔✔plant hormone or substance that promotes or regulates the growth and
development of plants. Produced at sites where cells are dividing, primarily in the shoot
tips. Auxin-like compounds may be synthetically produced.
✔✔available water - ✔✔water remaining in the soil after gravitational water has drained
and before the permanent wilting point has been reached.
✔✔axial transport - ✔✔movement of water, minerals, or photosynthates longitudinally
within a tree.
✔✔axillary bud - ✔✔bud in the axil of a leaf; lateral bud.
✔✔back cut - ✔✔cut made on a tree trunk or branch, opposite from and toward the
notch, face cut, or undercut, to complete felling or branch removal.
✔✔bactericide - ✔✔pesticide that is used to kill or inhibit bacteria in plants or soil.
✔✔balance (rigging) - ✔✔in rigging, a technique for lowering a limb without allowing
either end to drop.
✔✔balled and burlapped (B&B) - ✔✔tree or other plant dug and removed from the
ground for replanting, with the root system and soil wrapped in burlap or a burlap like
fabric.
✔✔barber chair - ✔✔dangerous condition created when a tree or branch splits upward
vertically from the back cut, slab up.
✔✔bare root - ✔✔tree or other plant removed from the ground for replanting without soil
around the roots.
✔✔bark tracing - ✔✔cutting away torn or injured bark to leave a smooth edge.
✔✔basal rot - ✔✔decay of the lower trunk, trunk flare, or buttress roots. Also called butt
rot.
✔✔bend - ✔✔type of knot used to join two rope ends together. Contrast with hitch.
✔✔bend radius - ✔✔radius of an object around which a line passes.
, ✔✔bend ratio - ✔✔ratio of the diameter of a branch, sheave, or other object to the
diameter of the rope that is wrapped around it.
✔✔best management practices (BMPs) - ✔✔best-available, industry-recognized
courses of action, in consideration of the benefits and limitations, based on scientific
research and current knowledge.
✔✔bight - ✔✔curve or arc in a rope between the working end and the standing part.
✔✔biological control - ✔✔method of managing plant pests or weeds through the use of
natural predators, parasites, or pathogens.
✔✔biorational control product - ✔✔(1) control product or pesticide formulated from
naturally occurring plant extracts, microbes, or microbial by-products that poses very
low risk to nontarget organisms. (2) control product or pesticide that has limited
environmental persistence and poses very low risk to nontarget organisms.
✔✔bipinnate - ✔✔double pinnate. Contrast with palmate and pinnate.
✔✔biotic disorder - ✔✔disorder caused by an infectious living agent.
✔✔Blake's hitch - ✔✔friction knot climbers use, sometimes in place of the tautline hitch
or Prusik knot.
✔✔blight - ✔✔any disease or disorder, regardless of the causal agent, that kills young
plant tissues.
✔✔block - ✔✔(1) heavy-duty pulley used in rigging. Designed for dynamic loading. (2)
casing enclosing one or more parallel pulleys.
✔✔body-thrust - ✔✔method of ascending a tree using a climbing rope.
✔✔bollard - ✔✔post on which wraps can be taken with a rope to tie it off or to provide
friction for control.
✔✔botanical pesticide - ✔✔pesticides derived from plants.
✔✔box cable system - ✔✔tree cabling system that forms closed polygons; used to join
together more than three stems.
✔✔bracket - ✔✔British English term for the fruiting body of a decay fungus. See conk.
WITH ANSWERS GRADED A+
✔✔aggregate - ✔✔(1) close cluster of mix of small particles of soil and/or organic matter
of varying sizes that are bonded together; sand, gravel, or small rocks in soil; and/or
sand, gravel, or small rocks used under paved surfaces. (2) clusters of flowers or fruits
that appear as a single unit. (3) individual tree crowns that form a canopy.
✔✔Air excavation device, air excavator - ✔✔device that directs a jet of highly
compressed air to excavate soil. Used within the root zone of trees to avoid or minimize
damage to the roots, or near underground structures such as pipes and wires to avoid
or minimize damage to them.
✔✔air terminal - ✔✔uppermost point of a tree lightning protection system.
✔✔aircraft cable - ✔✔steel wire rope of various constructions designated by the number
of strands in the rope and the number of wires in each strand. Commonly used in
cabling in Australia and New Zealand.
✔✔allelochemical - ✔✔substance produced naturally by plants as part of a defense
against pests and other plants. May adversely affect the growth and development of
other plants.
✔✔allelopathy - ✔✔chemical effect or inhibition of growth or development of plants that
is induced by allelochemicals
✔✔alternate - ✔✔pertaining to bud or leaf arrangement, one leaf or bud at each node,
situated at alternating positions along the stem. In this arrangement, the leaves are not
directly across from each other. Contrast with opposite and whorled.
✔✔amon-eye nut - ✔✔specialized nut used in cabling trees that has a large eye for
attaching a cable to a threaded rod.
✔✔anaerobic - ✔✔without oxygen. Process that occurs in the absence of oxygen.
✔✔anchor hardware - ✔✔hardware to which the cable termination is affixed in a cabling
or guying installation.
✔✔angiosperm - ✔✔plant with seeds borne in an ovary. Consists of two large groups:
monocotyledons (grasses, palms and related plants) and dicotyledons (most woody
trees, shrubs, herbaceous plants, and related plants). Contrast with gymnosperm.
✔✔anion - ✔✔ion that carries a negative charge. Contrast with cation.
,✔✔ANSI A300 - ✔✔In the United States, industry-developed, national consensus
standards of practice for tree care.
✔✔ANSI Z133.1 - ✔✔In the United States, industry developed, national consensus
safety standards of practice for tree care.
✔✔anthocyanin - ✔✔red or purple pigment responsible for those colors in some parts of
trees and other plants. Compare to carotenoid.
✔✔antigibberellin - ✔✔plant growth regulator that inhibits the action of the plant
hormone gibberellin, which, among other things, regulates cell elongation.
✔✔antitranspirant - ✔✔substance applied to the foliage of plants to reduce water loss
(transpiration).
✔✔apical bud - ✔✔bud at the tip of a twig or shoot.
✔✔apical control - ✔✔inhibition of lateral buds, decreasing from the top down, by apical
buds over many seasons, resulting in trees with an excurrent growth form.
✔✔apical dominance - ✔✔condition in which the terminal bud inhibits the growth and
development of the lateral buds on the same stem formed during the same season.
✔✔apical meristem - ✔✔growing point at the tips of shoots and roots.
✔✔apoplasm - ✔✔free spaces in plant tissue. Includes cell walls and intracellular
spaces. Contrast with symplasm.
✔✔appropriate response process (ARP) - ✔✔method of systematically assessing plant
health and client needs to determine which course of action, if any, is recommended.
✔✔approved - ✔✔in the context of guidelines, standards, and specifications, that which
is acceptable to federal, state, provincial, or local enforcement authorities or is an
accepted industry practice.
✔✔arboriculture - ✔✔practice and study of the care of trees and other woody plants in
the landscape.
✔✔arborist block - ✔✔heavy-duty pulley with an integrated connection point (bushing
for attaching a rope sling), a rotating sheave for the rope, and extended cheek plates.
Used in tree rigging operations.
✔✔ascender - ✔✔piece of gear that enables a climber to ascend a rope. Attached to
the rope, it will grip in one direction (down) and slide in the other (up).
,✔✔augmentation - ✔✔in Plant Health Care, the release of beneficial organisms to
suppress pest insect or mite populations.
✔✔auxin - ✔✔plant hormone or substance that promotes or regulates the growth and
development of plants. Produced at sites where cells are dividing, primarily in the shoot
tips. Auxin-like compounds may be synthetically produced.
✔✔available water - ✔✔water remaining in the soil after gravitational water has drained
and before the permanent wilting point has been reached.
✔✔axial transport - ✔✔movement of water, minerals, or photosynthates longitudinally
within a tree.
✔✔axillary bud - ✔✔bud in the axil of a leaf; lateral bud.
✔✔back cut - ✔✔cut made on a tree trunk or branch, opposite from and toward the
notch, face cut, or undercut, to complete felling or branch removal.
✔✔bactericide - ✔✔pesticide that is used to kill or inhibit bacteria in plants or soil.
✔✔balance (rigging) - ✔✔in rigging, a technique for lowering a limb without allowing
either end to drop.
✔✔balled and burlapped (B&B) - ✔✔tree or other plant dug and removed from the
ground for replanting, with the root system and soil wrapped in burlap or a burlap like
fabric.
✔✔barber chair - ✔✔dangerous condition created when a tree or branch splits upward
vertically from the back cut, slab up.
✔✔bare root - ✔✔tree or other plant removed from the ground for replanting without soil
around the roots.
✔✔bark tracing - ✔✔cutting away torn or injured bark to leave a smooth edge.
✔✔basal rot - ✔✔decay of the lower trunk, trunk flare, or buttress roots. Also called butt
rot.
✔✔bend - ✔✔type of knot used to join two rope ends together. Contrast with hitch.
✔✔bend radius - ✔✔radius of an object around which a line passes.
, ✔✔bend ratio - ✔✔ratio of the diameter of a branch, sheave, or other object to the
diameter of the rope that is wrapped around it.
✔✔best management practices (BMPs) - ✔✔best-available, industry-recognized
courses of action, in consideration of the benefits and limitations, based on scientific
research and current knowledge.
✔✔bight - ✔✔curve or arc in a rope between the working end and the standing part.
✔✔biological control - ✔✔method of managing plant pests or weeds through the use of
natural predators, parasites, or pathogens.
✔✔biorational control product - ✔✔(1) control product or pesticide formulated from
naturally occurring plant extracts, microbes, or microbial by-products that poses very
low risk to nontarget organisms. (2) control product or pesticide that has limited
environmental persistence and poses very low risk to nontarget organisms.
✔✔bipinnate - ✔✔double pinnate. Contrast with palmate and pinnate.
✔✔biotic disorder - ✔✔disorder caused by an infectious living agent.
✔✔Blake's hitch - ✔✔friction knot climbers use, sometimes in place of the tautline hitch
or Prusik knot.
✔✔blight - ✔✔any disease or disorder, regardless of the causal agent, that kills young
plant tissues.
✔✔block - ✔✔(1) heavy-duty pulley used in rigging. Designed for dynamic loading. (2)
casing enclosing one or more parallel pulleys.
✔✔body-thrust - ✔✔method of ascending a tree using a climbing rope.
✔✔bollard - ✔✔post on which wraps can be taken with a rope to tie it off or to provide
friction for control.
✔✔botanical pesticide - ✔✔pesticides derived from plants.
✔✔box cable system - ✔✔tree cabling system that forms closed polygons; used to join
together more than three stems.
✔✔bracket - ✔✔British English term for the fruiting body of a decay fungus. See conk.
