What term describes a chemical that causes the leaves of a plant to drop prematurely?

The term that describes a chemical that causes the leaves of a plant to drop prematurely is a defoliant. Defoliants are specifically designed to induce leaf drop, which can be a desirable process in agricultural practices such as harvesting crops that have finished their growth cycle. By promoting defoliation, these chemicals help facilitate easier harvesting and improve the overall efficiency of agricultural production.

Desiccants, while they can cause moisture loss from plants, do not specifically target leaf drop. Disinfectants are used to kill pathogens and are not designed for affecting plant foliage, and diluting refers to reducing the concentration of a substance with a solvent, which does not apply to the concept of promoting leaf drop. Thus, defoliant is the accurate term for a chemical that induces premature leaf drop in plants.