ISA Certified Arborist Practice Exam 2025 – All-in-One Resource for Comprehensive Exam Success!

Excessive pruning can lead to significant stress in trees, making them more susceptible to a variety of pests and diseases. When a tree is over-pruned, it may lose too much foliage, which is crucial for photosynthesis. This reduction in leaf area can weaken the tree, diminishing its overall health and vigor. Stress from excessive pruning may also lead to an imbalance in the tree's ability to produce energy and compete for resources, ultimately increasing vulnerability to insects and pathogens that target weakened plants, and thus potentially leading to long-term health issues.

Additionally, while pruning can be beneficial when done correctly, excessive pruning can disrupt the tree’s natural growth patterns and its ability to heal. A healthy tree should have a balanced structure, and when cut excessively, it may not have the resilience to recover effectively. This creates a scenario where the tree is not only stressed but is also unable to defend itself properly against biological threats.