What defines a selective herbicide?

What defines a selective herbicide?

• A. Kills only certain plant species without adversely affecting the growth of others
• B. Kills all plants
• C. Moves through the plant to kill it
• D. Is applied to soil to inhibit seed germination

Answer: (A)

Selective herbicides target specific plant species or groups while leaving others unharmed. This works because different plants have distinct physiology or metabolism: they may have the herbicide’s target enzyme, or they may absorb, translocate, or detoxify the chemical at different rates. As a result, one crop or group of plants survives while other species are harmed. For example, some herbicides exploit hormone pathways that are essential in broadleaf weeds but not in grasses, so they kill broadleafs without injuring grasses. A non-selective herbicide would kill many species, not just a few, so it isn’t selective. A herbicide described as moving through the plant highlights systemic action, not which plants are affected. A soil-applied product that inhibits seed germination emphasizes timing or method, not species specificity.

Selective herbicides target specific plant species or groups while leaving others unharmed. This works because different plants have distinct physiology or metabolism: they may have the herbicide’s target enzyme, or they may absorb, translocate, or detoxify the chemical at different rates. As a result, one crop or group of plants survives while other species are harmed. For example, some herbicides exploit hormone pathways that are essential in broadleaf weeds but not in grasses, so they kill broadleafs without injuring grasses. A non-selective herbicide would kill many species, not just a few, so it isn’t selective. A herbicide described as moving through the plant highlights systemic action, not which plants are affected. A soil-applied product that inhibits seed germination emphasizes timing or method, not species specificity.