2,4-D selectivity: 2,4-D is selective for which plant type?

• A. Grasses
• B. Algae
• C. Broadleaf plants
• D. Aquatic macrophytes

Answer: (C)

Selective herbicides exploit differences between plant groups. 2,4-D acts as a synthetic auxin, meaning it mimics a natural plant growth hormone. When broadleaf plants (dicots) take it up, it disrupts the normal growth signals in the growing tissues, causing uncontrolled, abnormal growth and tissue damage that leads to the plant’s death. Grasses (monocots) are less affected because their physiology and metabolism handle auxin-like compounds differently, so they can survive while broadleaf weeds are killed. It isn’t used to target algae or aquatic macrophytes, which require different modes of action. So, 2,4-D is selective for broadleaf plants.