Certified Arborist Practice Exam

Curling and cupping of foliage and parallel venation is often a result of:

1. Herbicide damage

2. Nematodes

3. Allelopathy

4. Sign

The correct answer is: Sign

The description of curling and cupping of foliage along with parallel venation is indicative of symptoms that typically arise from herbicide damage. Herbicides can disrupt normal plant growth patterns, leading to abnormal leaf structures. This is especially true for systemic herbicides that are absorbed and translocate throughout the plant. The curling and cupping may be associated with physiological disruptions caused by the chemicals, often resulting in the leaves taking on a distorted appearance. Cupping or curling leaves can commonly be observed in plants exposed to specific herbicides, and the presence of parallel venation indicates that the damage is affecting the plant's vascular and physiological processes. This type of damage is prevalent in certain sensitive plant species and can lead to other developmental issues if exposure continues. While nematodes can cause damage to roots and affect a plant’s vigor or lead to stunted growth, their impact is less directly visualized in the leaves compared to what herbicides can accomplish. Allelopathy, which involves the release of biochemicals by plants, primarily affects nearby plant growth rather than causing specific foliar deformities. Therefore, the symptoms described closely align with effects typically seen from herbicide application rather than other factors.