Certified Arborist Practice Exam

Root collar excavation should be done if decay is suspected at the root flare or in the major support roots. Excavating the root collar, or the area where the base of the tree trunk meets the ground, can help identify and address any decay that may be present. Option A, reaction wood, refers to the type of wood that forms in response to strain or tension, and is not directly related to decay. Option B, false, does not provide any useful information and is not a correct response to the question. Option D, mitigation, refers to the action of reducing or preventing a problem, which is not specific to decay at the root flare or major support roots.