ISA Study Guide 2026

A drop zone is a designated clear area below the work where cut branches and sections can fall safely, protecting ground workers and bystanders from being struck by falling material.

Nitrogen is mobile in the plant, so deficiency symptoms appear first on older leaves as nitrogen is redirected to new growth.

Fertilization is most effective in late fall (after leaf drop, while soil is still warm) or early spring (before bud break). Late fall applications allow root absorption and storage; spring applications support the flush of new growth.

The standard hand signal for 'stop' in crane operations is extending one arm with a closed fist. This is part of the universally recognized crane hand signal system used across industries.

Respiration is the metabolic process where trees break down sugars (produced during photosynthesis) to release energy for various life processes. This process requires oxygen, which is why soil aeration is critical for root health, as roots must also respire. Photosynthesis creates sugars, while respiration consumes them to produce energy.

A 2–4 inch mulch layer conserves moisture and moderates temperature without creating anaerobic conditions at the root flare.