Maryland Pesticide Applicator Category 3: Ornamental and Turf Practice Test 2026 - Free Pesticide Applicator Practice Questions and Study Guide

Selective and nonselective herbicides differ in how broad their effect is on plants. Selective herbicides are designed to kill only certain weed species while leaving the desirable plants (like turfgrass or ornamentals) unharmed. They work by exploiting differences in plant biology so that weeds absorb or are metabolized by the chemical differently than the plants you want to protect. In a lawn, a selective herbicide will target broadleaf weeds such as dandelions while sparing the grass.

Nonselective herbicides, on the other hand, kill most or all green plants they contact, making them useful for clearing an area where you don’t want any vegetation (site preparation, around hardscapes, etc.). They must be used with care where desirable plants are present.

So the correct idea is that selective kills some plants and nonselective kills all plants. The other statements mix up which plants are affected or bring in unrelated effects.