Certified Arborist Practice Exam

Microscopic worms that sometimes feed on trees and may carry diseases are:

1. Nematodes

2. Bacteria

3. Allelopathy

4. Phloem

The correct answer is: Nematodes

Nematodes are microscopic, often parasitic worms that inhabit a variety of environments, including soil and plant tissues. They are known to feed on roots and other parts of trees, affecting the health of the plants. Some species of nematodes can carry pathogens, introducing diseases that can severely impact tree vitality and longevity. Their role in both nutrition and disease transmission in trees makes them significant pests in arboriculture. This understanding is crucial for arborists when assessing tree health and implementing management practices, making the identification of nematodes essential in the preservation of tree ecosystems. In contrast, bacteria are microscopic organisms that can cause disease but are not worms. Allelopathy refers to the chemical inhibition of one plant by another, which is a different phenomenon pertaining to plant interactions. Phloem is a type of tissue in vascular plants responsible for nutrient transport, not a type of organism or disease carrier.