Certified Arborist Practice Exam

What does nitrogen fertilization potentially compromise in a tree?

1. Dissolved in water

2. Injected below the absorbing roots

3. Wilting, marginal burning, dieback

4. Fertilizer salts causing symptoms

The correct answer is: Wilting, marginal burning, dieback

Nitrogen fertilization can potentially compromise the health of a tree by leading to symptoms such as wilting, marginal burning of leaves, and dieback. This occurs because an excess of nitrogen promotes rapid growth, which can stress the tree. When trees grow too quickly, they may be more susceptible to environmental stresses and diseases, making them less resilient overall. Furthermore, excessive nitrogen levels can disrupt the balance of nutrients in the soil, leading to deficiencies of other essential nutrients like potassium and magnesium. These imbalances can exacerbate physiological problems, resulting in the symptoms noted, such as wilting and dieback. In contrast, the other options address different aspects of tree care and health. The mention of being "dissolved in water" relates to how nutrients are transported but does not directly tie to the compromise caused by excessive nitrogen. Injected treatments below the absorbing roots focus on application methods rather than the consequences on tree health. Similarly, while fertilizer salts causing symptoms is valid in certain contexts—particularly regarding salt build-up—it is not as directly linked to the specific effects of nitrogen fertilization on tree physiology as the wilting and dieback symptoms. Therefore, the option regarding wilting and related symptoms directly aligns with the negative impact of excessive nitrogen on tree health