“Active ingredient” means in the case of:
1. A pesticide, other than a plant regulator, defoliant or desiccant, an ingredient which will prevent, destroy, repel or mitigate insects, nematodes, fungi, rodents, weeds or other pests.
2. A plant regulator, an ingredient which, through physiological action, will accelerate or retard the rate of growth or rate of maturation or otherwise alter the behavior of ornamental or crop plants or the produce thereof.
3. A defoliant, an ingredient which will cause the leaves or foliage to drop from a plant.
4. A desiccant, an ingredient which will artificially accelerate the drying of plant tissue.