Illinois Field Crop Applicators Practice Test

What symptom is associated with photosynthesis inhibitors?

1. Stalk bending

2. Yellowing of the leaves

3. Twisting of leaves

4. Cupping of leaves

The correct answer is: Yellowing of the leaves

The symptom associated with photosynthesis inhibitors is the yellowing of the leaves. Photosynthesis inhibitors disrupt the process by which plants convert sunlight into energy, leading to a deficiency in chlorophyll production. Chlorophyll is the pigment responsible for the green color in leaves, so when its production is hindered, the leaves begin to exhibit a yellowing or chlorosis effect. This symptom indicates that the plant is not efficiently using light energy and is struggling to carry out essential metabolic processes. In contrast, symptoms such as stalk bending, twisting of leaves, and cupping of leaves are typically associated with other types of herbicide actions or environmental stress factors, rather than specifically indicating issues caused by photosynthesis inhibitors. Yellowing of the leaves is a clear and distinctive signal of the impact that these inhibitors have on a plant's health and growth.