Certified Arborist Test Study Guide 2026

Minimum approach distance (MAD) is the closest distance a qualified line clearance worker may approach energized electrical conductors without appropriate insulation.

Topping is a severe and improper pruning practice that involves cutting back large branches to stubs, often between nodes, without regard for branch collar or natural growth points. This practice primarily utilizes heading cuts, which stimulate weak, rapid regrowth and can severely damage the tree's structure, health, and aesthetic appeal.

Water-holding cavities promote continued decay by maintaining moisture that supports fungal growth. While drilling drain holes was once common, current practice focuses on overall risk assessment rather than cavity treatment.

A variety (often denoted by 'var.' in botanical names) is a naturally occurring subdivision within a species that possesses distinct characteristics. These traits are stable and heritable, allowing the group to breed true from seed. Unlike cultivars, varieties arise naturally in the wild without human intervention.

Armillaria mellea and related species produce three highly diagnostic signs used together to confirm infection: flat white mycelial fans (which smell mushroom-like) between the bark and wood at the root collar; dark, shoestring-like rhizomorphs running under the bark or through the soil; and clusters of honey-colored (amber) mushrooms with a ring on the stipe fruiting at the base in late summer or fall. No other root disease produces all three signs.

Rigging is the process of removing branches from trees or bringing them down entirely using ropes and other tools. Cutting a wedge into a branch or tree trunk before performing a reverse cut to complete the cut is known as notching. Branches are lowered to the earth during landing. Arborists ought to create a landing area close to the tree. Large branches and leaves are expected to fall in this area during removal. When a moving load is quickly stopped, shock-loading refers to the sudden application of a dynamic force on the rope or rigging apparatus.