Microbial herbicides — Which of the following antibiotic-like herbicides is reported to be selectively effective against dicot (broadleaf) weeds?

Introduction / Context:Several microbial metabolites exhibit herbicidal properties and have been explored as “bioherbicides.” Understanding selectivity—whether a material targets dicots versus monocots—is essential for crop safety and weed spectrum management, especially in integrated weed control programs.

Given Data / Assumptions:

• Herbicidins are nucleoside antibiotics from Streptomyces with herbicidal activity, notably toward dicots.
• Bialaphos is a tripeptide pro-herbicide that releases glufosinate; it is broadly non-selective.
• Cycloheximide and anisomycin are protein synthesis inhibitors, primarily referenced as antifungal or experimental tools, not selective field herbicides against dicots.

Concept / Approach:Selectivity hinges on metabolic targets and plant physiology. Herbicidin A/B disrupt specific biochemical pathways that dicot weeds are more sensitive to, allowing selectivity under labeled uses. In contrast, glufosinate (from bialaphos) is non-selective and widely injures both monocots and dicots unless crop-tolerant traits are present.

Step-by-Step Solution:

Verification / Alternative check:Research reports and screening studies highlight activity of herbicidin analogs against broadleaf weeds with reduced injury to certain monocots under specific conditions.

Why Other Options Are Wrong:

Common Pitfalls:Assuming all microbially derived herbicides are selective; many act broadly and can harm crops without resistant traits.

Final Answer:Herbicidin A and Herbicidin B.