What are curling and cupping of the foliage, and parallel venation, common symptoms of?

Curling and cupping of foliage, along with parallel venation, are indeed common symptoms associated with herbicide damage. When herbicides are applied, especially those that affect the growth hormones of plants, the foliage can exhibit abnormal growth patterns. Curled or cupped leaves signify a physiological response to the herbicide exposure, reflecting how the chemicals interfere with the plant's normal growth processes.

Parallel venation, particularly prominent in monocotyledonous plants, can also become more pronounced or distorted when plants are affected by certain herbicides due to how these chemicals disrupt typical leaf development and vein formation. Understanding these symptoms is crucial for diagnosing herbicide-related issues, especially in environments where pesticide usage is common.

In contrast, water stress would typically present with symptoms like wilting or browning of leaf edges rather than curling and cupping. Fungal infections might cause other types of leaf damage, such as spots or mildew, rather than the distinct shapes noted. Insect damage usually results in visible signs like holes or leaf mining patterns rather than the specific alterations in shape and vein arrangement seen with herbicide exposure. Recognizing these symptoms allows arborists to identify and address the causes of plant distress effectively.