Why Herbicide Modes and Sites of Action Differ
Weed scientists and agronomists frequently intersperse the
terms of pesticide modes of action (MOA) and sites of action (SOA). What do
they really mean?
Although the two are used interchangeably, they mean differ things.
MOA refers to how a pesticide kills a pest. For example, Select, a soybean herbicide, curtails lipid synthesis in targeted weeds. Thus, its mode of action is a lipid synthesis inhibitor. It works by binding to the Acetyl-COA carboxylase (ACCase) enzyme. Thus its site of action is as an ACCase inhibitor. Herbicides can also bind to specific proteins in a weed, disrupting plant processes. Most herbicides bind to a single protein.