- A substance used to kill, control, repel, or mitigate any pest. Insecticides, fungicides, rodenticides, herbicides, and germicides are all pesticides. Environmental Protection Agency regulates pesticides under authority of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). In addition, under FIFRA, a substance used as a plant regulator, defoliant, or desiccant is defined as a pesticide and regulated accordingly. All pesticides must be registered and carry a label approved by EPA.
- A substance that kills harmful organisms (for example, an insecticide or fungicide).