Buggy-whipping and malformed brace roots on corn are symptoms of:

• A. Amino acid synthesis inhibitors
• B. Seedling growth regulators
• C. Photosynthesis inhibitors
• D. Growth regulator herbicides

Answer: (D)

Buggy-whipping and malformed brace roots in corn are indeed symptoms associated with the application of growth regulator herbicides. Growth regulator herbicides interfere with the normal growth processes of the plant, which can lead to distorted growth patterns. The term "buggy-whipping" refers to the leaves that form in a twisted or distorted manner, resembling a whip, while malformed brace roots are indicative of disrupted root development, which can affect the plant's stability and nutrient uptake.

These symptoms are specifically linked to herbicides that function as growth regulators, altering hormonal balance and growth patterns rather than directly impacting photosynthesis or amino acid synthesis, which would lead to different types of plant stress and symptoms. Recognizing the impacts of growth regulator herbicides is important for understanding how these products can affect crop development and management practices.