What symptom indicates that Bromoxynil has been applied to a crop?

When Bromoxynil is applied to a crop, the symptom that is indicative of its presence is the appearance of blistered necrotic spots on leaves. Bromoxynil is a selective contact herbicide primarily used to control broadleaf weeds. Its mode of action involves inhibiting photosynthesis, which can lead to the characteristic leaf damage. The blistered necrotic spots are a direct result of the herbicide causing localized cell injury to the plant tissue, effectively disrupting normal physiological functions. This visible symptom serves as a clear indicator of the herbicide's application and its impact on the crop.

The other symptoms listed, such as bronzing of lower leaves, epinasty followed by necrosis, and yellowing and stunting, are associated with different types of herbicide damage or plant stresses and do not specifically denote the use of Bromoxynil.